Sleep is vital for every aspect of human health. Adults generally need seven to nine hours per night.^1,2 The importance of adequate sleep has been born out in extensive research, and most people are now aware that regularly getting enough quality sleep helps prevent various chronic diseases. Better sleep quality has even been linked to slower biological aging, while chronically sleeping too much or too little has been associated with a shorter lifespan.^3-5

Perhaps less well appreciated is that suboptimal sleep undermines the performance of the human mind and body.^6,7 For instance, inadequate sleep correlates with worse grades and lower likelihood of graduation among college students.⁸ Suboptimal sleep also undermines individuals’ work performance—and when extrapolated across populations, the economic performance of businesses and nations.^9-11 In fact, Deloitte, a business consultancy firm, has described sleep as “the ultimate performance enhancer.”¹⁰

And yet, one in three U.S. adults report sleeping less than seven hours per 24-hour period.^12,13 This means that one-third of adults may stand to improve their cognitive and physical performance by sleeping more and better.

This Protocol should interest the one in three adults who do not get optimal sleep and who may be underperforming their well-rested peers as a result. Anyone who gets “enough” sleep, but nevertheless wants to improve the quality of their sleep (and thereby potentially enhance their quality of life and performance), may be interested in reading this Protocol as well.

In this Protocol, we will summarize the scientific evidence related to various means of improving sleep quantity and/or quality. In general, we have attempted to focus on scientific evidence derived from studies in which the participants were generally healthy. While overt sleep disorders like insomnia and sleep difficulties due to serious underlying diseases are not addressed in detail here, this Protocol provides tips and strategies for people who may have some room to improve their sleep regimen. We call this approach Sleep Hacking.

The Stages of Sleep

Sleep has two distinct stages that occur cyclically and are marked by different types of brain activity: non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. On a typical night, sleep consists of three to six NREM-REM cycles, lasting about 90–120 minutes each and sometimes interrupted by short bouts of wakefulness (Fig. 1).^14,15 Healthy, restorative sleep includes both NREM and REM sleep.¹⁶

The drive to sleep is normally initiated by the body’s internal circadian clock. On an electroencephalogram (EEG)—a tool used during a sleep study for measuring brain electrical activity—the process of falling asleep appears as a gradual transition from predominantly small, high-frequency waves to larger, slower waves. This shift marks the progression from wakefulness to deep sleep stages. During REM sleep, however, the EEG shows a return to smaller, high-frequency waves, reflecting a more active brain state despite the body remaining at rest.^14,16

NREM sleep represents about 75–80% of total sleep time and is characterized by reduced responsiveness to internal and external stimuli, decreased core body and brain temperatures, lower muscle tone, and slower breathing and heart rates. NREM sleep itself is categorized in three stages based on brain wave activity^15,16:

• Stage 1 (N1) is when the body is transitioning to sleep. Heartbeat, eye movement, and brain waves begin to slow down.¹⁶ Sometimes muscle twitches (“hypnic jerks”) occur during this sleep stage, which lasts only a few minutes, representing 2–5% of total sleep time.¹⁵
• Stage 2 (N2) involves deepening of sleep, with a higher threshold for waking, further slowing of heart and breathing rates, and reductions in temperature and muscle activity.¹⁴ Short bursts of brain activity (electrical events known as sleep spindles and K-complexes) occur throughout N2 and play a role in keeping us asleep, building memory, and toning brain function.¹⁶ Ideally, about 45–55% of total sleep time is spent in N2.¹⁵ N2 and N1 sleep are sometimes referred to jointly as core sleep.
• Stage 3 (N3), known as deep or slow-wave sleep, is the most difficult to awaken from. Deep sleep is believed to be important for tissue regeneration and repair, as well as metabolic and immune regulation, hormone balance, and memory.^16,17 Most slow-wave sleep occurs in the first few sleep cycles.¹⁸ Its duration generally makes up 13–23% of total sleep time in younger adults, but diminishes with age and may be absent in elderly individuals.¹⁵

A normal sleep cycle involves gradual transitioning through N1, N2, and N3. Deep sleep then gives way to lighter N2 sleep and finally a period of REM sleep (Fig. 1).¹⁵

REM sleep generally occurs in 10–20-minute episodes at the end of sleep cycles, accounting for 20–25% of total sleep time. It is characterized by rapid jerky eye movements and brain electrical activity similar to awake time.¹⁶ REM sleep appears to be a time of intellectual and emotional processing, with vivid dreaming as well as muscle twitching and fluctuations in breathing and heart rate.^14-16 In contrast with deep sleep, periods of REM sleep tend to become longer with each successive sleep cycle throughout the night.^15,16 REM sleep concludes with a return to N1, sometimes with a brief period of wakefulness prior to the next sleep cycle.¹⁵

Figure 1: Example of Normal Sleep Architecture

Credit: Miller CB, Kyle SD, Melehan KL, Bartlett DJ. Methodology for the Assessment of Sleep. Sleep and Affect. 2015:65-90.¹⁹

Opportunities for Sleep Optimization: Falling Asleep & Staying Asleep

For many people reading this overview, opportunities to leverage sleep optimization to enhance performance will center around one of two themes, or sometimes both—making it easier to fall asleep or stay asleep.

The length of time it takes to fall asleep initially upon trying is called sleep latency. Normal sleep latency for adults is about 10 to 20 minutes.²⁰ Longer sleep latency over a prolonged period has been associated with cardiovascular health concerns like decreased heart variability and increased blood pressure.^21,22

Similarly, chronic trouble staying asleep is linked with several health problems as well.^23-25

If you experience frequent (three or more nights per week) trouble falling asleep or staying asleep over a long period of time (three months or longer), you should consult your doctor and ask about an insomnia evaluation.^26-28

This overview is not intended to be a resource for people with overt insomnia. Instead, people who experience occasional sleep trouble and/or feel they could benefit from taking steps to optimize their sleep are those for whom sleep hacking is a reasonable framework. Interestingly, research has suggested that sleep performance lies on a continuum ranging from self-identified good sleepers to overt insomniacs, with self-reported poor sleepers falling somewhere in between. Sleep hacking is a reasonable initial approach for those who feel they are poor sleepers but not those who experience severe debilitation due to insomnia.²⁷

Sleep Quantity & Quality

For most adults, seven to nine hours of sleep per night is recommended to optimize health and lower the risks of chronic diseases.^1,2 Importantly, healthy sleep is marked not only by sufficient quantity, but also good quality and appropriate timing.³⁶ For instance, a study using accelerometer-derived sleep data from almost 104,000 UK Biobank participants over a period of seven days found that sleep onset time between 10:00 p.m. and 10:59 p.m. was associated with the lowest incidence of cardiovascular disease.³⁷

Sleep health is a multi-dimensional concept that lacks a consistent definition, but can be thought of as sleep-related well-being that is more than simply the absence of sleep pathology.^38,39 The following parameters are important to consider when evaluating sleep health^36,40:

• Duration: the amount of time asleep. In general, seven to nine hours of sleep per night is optimal for supporting good overall health in most adults.⁴¹
• Efficiency: the ease of falling and returning to sleep, measured as the proportion of intended sleep time that is actually spent sleeping. Sleep efficiency decreases with aging, and poor sleep efficiency may be a more important marker of health risks in elderly individuals than low sleep duration. Since sleep efficiency of less than 80% (ie, awake >20% of time in bed) has been correlated with poor health outcomes and increased mortality,⁴² a common target for sleep efficiency is 85%.⁴³
• Timing: the placement of bedtime and awakening time within the 24-hour day. Our internal circadian clock regulates rhythms of wakefulness and sleep, as well as cardiovascular, digestive, metabolic, and immune functions, and coordinates them with environmental cues such as cycles of light and darkness.⁴⁴ Synchronizing sleep with circadian rhythms is especially important for cardiometabolic health.^39,44
• Regularity/Variability: day-to-day variability in the sleep-wake schedule. Irregular sleep patterns promote circadian de-synchronization, inflammation, nervous system and stress response dysregulation, and gut microbiome disruption, taking a toll on cardiometabolic and overall health. On the other hand, consistent sleep patterns appear to support optimal health. For example, sleep patterns that do not vary by more than 30 to 60 minutes each day have been linked to better cardiovascular health.⁴⁵
• Satisfaction: the subjective assessment of sleep quality. This includes how one feels about their sleep immediately upon waking and throughout the following day, and may be based on such considerations as how one judges their comfort while sleeping, their ability to fall asleep, the ease with which they fall back to sleep, and the duration of their sleep.⁴⁶ In one study that included 109 university students, higher sleep satisfaction was more closely aligned with positive mood, sense of well-being, and life satisfaction than objective measures of sleep quality.⁴⁷
• Alertness/Sleepiness: the ability to remain attentive during waking hours. Excessive daytime sleepiness has been correlated with increased risks of cardiovascular disease and cognitive dysfunction, as well as poorer mental and physical performance and higher risk of accidents.^48-52 On the other hand, alertness is associated with better mood and cognitive, mental, and physical performance.⁵³

Both objective and subjective measures are important parts of a comprehensive sleep assessment. Sleep is typically assessed using polysomnography and actigraphy to provide objective sleep data and questionnaires to provide subjective information.

Polysomnography - The Sleep Study

When any type of sleep disorder is suspected, a diagnosis can be ascertained using polysomnography, also known as a sleep study. Polysomnography is the “gold standard” test in research studies that evaluate the effect of various interventions on sleep architecture and sleep parameters. It combines recordings of brain waves, eye movements, breathing patterns, and heart function to provide insight into body and brain activity during sleep. Polysomnography is generally performed in a supervised setting such as a sleep clinic.⁵⁴ The components of polysomnography can vary, but typically include^54,55:

• Electroencephalography (EEG) to measure brain electrical activity and thereby evaluate sleep architecture
• Electrocardiogram (ECG) to monitor heart electrical activity
• Electro-oculography (EOG) to detect eye movements and provide further information about REM and other sleep stages
• Electromyography (EMG) to provide information about muscle tension and limb movements
• Airflow sensors to assess the movement of air through the nose and mouth to detect episodes of apnea (paused breathing) or hypopnea (shallow breathing) and other disordered breathing patterns
• Pulse oximetry to measure blood oxygen levels and help detect correlations between oxygen levels, breathing, and arousals during sleep
• Plethysmography to monitor respiratory mechanics
• Video and sound recordings to detect sleep position and sleep events such as nightmares or night terrors, sleep talking or walking, and other sleep movements and sounds

After this data is collected, it is synthesized and analyzed in short time frames. Time needed to fall asleep, wakefulness after sleep onset, number and duration of arousals, early morning waking, and total sleep time can be ascertained, and sleep efficiency can be calculated. In addition, the amount of time spent in each sleep stage and frequency of events such as apneas or limb movements can be seen.⁵⁵

Despite its comprehensive nature, polysomnography’s usefulness is still limited in that it shows only a one- to two-night “snapshot,” which may miss sleep problems that occur intermittently.⁵⁴ It is also cumbersome, expensive, and removes the patient from their natural sleep environment, such that the test procedure itself may interfere with normal sleep patterns. Home-based units that allow a patient to sleep in their own bed, can be used for multiple consecutive nights, and do not require an attendant are sometimes an option for clinically assessing sleep architecture, but do not provide the comprehensive assessment of a lab-based sleep study.⁵⁶ Home-based sleep studies may be reasonably accurate for many people. However, those who have many other health conditions or who think their at-home results might be inaccurate should consider a lab-based sleep study.⁵⁷

Actigraphy

Actigraphy is an objective method of monitoring rest and activity cycles by collecting data about body movement via a wearable device, such as on a wristband, that measures acceleration.⁵⁸ The actigraphy device can be worn day and night for long periods of time to provide an overview of a range of sleep and activity parameters. It has the advantages of being easy to use, non-invasive, and lower in cost than polysomnography, but does not directly measure sleep, and does not include data regarding sleep architecture or breathing abnormalities.^59-61 Although actigraphy has been shown in multiple studies to reasonably reflect sleep-wake cycles, compared with polysomnography, it tends to overestimate total sleep time and is more likely to be inaccurate in individuals with poor sleep. This is mainly because it cannot distinguish non-moving awake time from sleep.⁶⁰

Pittsburgh Sleep Quality Index

The Pittsburgh Sleep Quality Index (PSQI) is the most commonly used sleep questionnaire and is considered the gold standard for measuring self-perceived sleep quality. Used in both clinical and research settings, it consists of 24 questions pertaining to the previous 30 days, five of which can be answered by a partner who shares the same room. In addition to questions about falling asleep, staying asleep, sleep duration, sleep efficiency, and sleep disturbance, there are also questions about daytime sleepiness and sleep medication use.^62,63 Although the usefulness of PSQI has been validated in multiple clinical trials, it is limited by its dependence on accurate memory and should be used in conjunction with objective assessments, especially in elderly adults.⁶⁴

Sleep Disorder Questionnaires

Other questionnaires are used to aid in the diagnosis and evaluation of sleep disorders, such as the Athens Insomnia Scale (AIS), Insomnia Severity Index (ISI), Mini Sleep Questionnaire (MSQ), and Epworth Sleepiness Scale (ESS).⁶²

Sleep Diary

A sleep diary is a widely used method for subjectively describing sleep quality. Entries into a sleep diary are made in the morning immediately after waking and allow for estimates of sleep parameters such as the time between going to bed and falling asleep, time to waking after falling asleep, total sleep time, total time in bed, sleep efficiency, and overall satisfaction.⁶² A sleep diary may be useful in screening for sleep problems, but depends on daily compliance, memory function, and reporting ability. Notably, there is a common tendency to overestimate sleep duration and underestimate time spent awake in bed.⁵⁶

Nutrients

Melatonin

Reported Dosage: 0.3–10 mg, taken about 30 minutes before bedtime

Melatonin is a hormone produced mainly by the pineal gland in the brain in response to darkness. It is found throughout the body and in nearly all body fluids.⁶⁵ Although levels decline with aging, rhythmicity is generally maintained throughout life, with peak blood levels occurring around 3 AM.⁶⁶ Because melatonin’s main function is regulating circadian systems, it has potential usefulness in repairing circadian disruption, such as due to shift work or travel through time zones.^67,68 It has also been shown to scavenge free radicals, reduce inflammation, modulate immune function, and support mitochondrial function. Furthermore, melatonin levels are lower in those with chronic metabolic, cardiovascular, and neurologic diseases.^65,69 The safety of melatonin use in healthy adults, including elderly individuals, at usual doses (generally between 0.3 mg and 10 mg nightly) has been demonstrated in multiple randomized controlled trials and meta-analyses.⁷⁰ The effectiveness of melatonin supplementation for promoting sleep in healthy people has been demonstrated using doses as low as 0.1 mg and up to 6 mg. For instance, dosages of 0.3 mg were shown in studies conducted in the mid-1990s by researchers at the Massachusetts Institute of Technology to promote sleep onset without disrupting sleep architecture.^71,72

A 2014 systematic review of melatonin research included 35 randomized controlled trials with a total of 2,356 subjects. Findings from a subset of 15 of the included trials that had strictly healthy participants indicated melatonin, at doses of 1–6 mg, improved sleep and reduced daytime sleepiness. Other trials in the review showed melatonin helped resolve jet lag, but evidence for its benefits in shift workers was inconclusive.⁷³ A earlier meta-analysis of data from 17 randomized placebo-controlled trials with a total of 284 participants found melatonin supplementation improved sleep parameters, but the effects were small: in a subset of 15 trials in individuals who were either healthy or had insomnia but were otherwise healthy, the time needed to fall asleep decreased by 3.9 minutes, sleep efficiency improved by 3.1%, and total sleep time increased 13.7 minutes.⁷⁴ In one randomized, placebo-controlled, crossover trial that included 24 healthy participants aged 55 years and older who had no major sleep issues, 5 mg melatonin 30 minutes before bedtime in controlled experimental conditions increased sleep efficiency, mainly by increasing stage 2 NREM sleep and slightly shortening awakenings.⁷⁵

While standard melatonin supplements rapidly increase blood melatonin levels and can shorten the time needed to fall asleep, newer extended-release formulations have been found to sustain higher melatonin levels through the night in healthy individuals and hold promise for their potential to better maintain sleep through the night.^76-78

Magnesium

Reported Dosage: 72–500 mg elemental magnesium daily

Magnesium is involved in regulating nerve and muscle fiber activation, modulating excitability of the nervous system, and relaxing muscle tension. Low magnesium intake is common, and intracellular magnesium levels have been shown to diminish with aging while blood levels remain stable, making it difficult to detect deficiency. Even mild magnesium deficiency can contribute to insomnia, fatigue, and cognitive and mood problems.⁷⁹ In observational studies, those with the highest dietary magnesium intake reported better sleep quality, including less snoring and less daytime sleepiness. They were also less likely to report having a sleep duration of less than seven hours per night.^80,81

In a randomized, controlled, crossover trial in 12 healthy elderly participants, 20 days of magnesium supplementation reduced nighttime levels of the stress hormone cortisol and increased deep sleep (stage N3). The dose was 403 mg magnesium oxide (providing 243 mg of elemental magnesium) once daily for three days, then twice daily for three days, then three times daily for 14 days.⁸² In a randomized controlled trial in 46 elderly subjects with insomnia, 500 mg of elemental magnesium, taken as two divided doses of magnesium oxide daily for eight weeks, increased blood melatonin levels, decreased cortisol levels, and improved self-reported total sleep time, sleep efficiency, and time to sleep onset.⁸³ Another randomized controlled trial in 100 adults over 50 years of age with poor sleep found 320 mg magnesium (as magnesium citrate) per day for seven weeks improved sleep quality scores; however, those receiving placebo experienced a similar increase in sleep quality.⁸⁴

Magnesium in the form of magnesium-L-threonate has been shown in preclinical models to increase concentrations of magnesium in the plasma and central nervous system better than other forms.⁸⁵ In a randomized controlled trial, 80 people between ages 35 and 55 years with self-assessed sleep problems took 1 gram of a branded form of magnesium-L-threonate called Magtein, providing 72 mg of elemental magnesium, or a placebo daily for 21 days. Sleep and daily behaviors were measured subjectively using standardized questionnaires and objectively with an Oura Ring (a “smart” ring that tracks several biometrics and sleep metrics). Based upon the questionnaires, there was a significant improvement in the treatment group in behavior upon awakening, energy, daytime productivity, grouchiness, mood, and mental alertness compared with placebo. Objective assessments via the Oura Ring showed significant improvements in deep sleep score, REM sleep score, and light sleep time, as well as various improvements in activity scores throughout the day.⁸⁶

Glycine

Reported Dosage: 3 grams taken 30–60 minutes before bedtime

Glycine is a non-essential amino acid with many functions in the body. In the nervous system, glycine acts as an inhibitory neurotransmitter that helps reduce involuntary muscle movement during sleep. It also activates receptors that lead to reduced core body temperature during sleep, and may modulate orexin neuron signaling, which could counteract wakefulness.^87-89 Glycine also plays a role in regulating immune function and inflammation and is important for protein synthesis.⁹⁰

In a randomized crossover trial, seven healthy men took either 3 grams glycine or placebo 30 minutes before bedtime on three consecutive nights; in a second phase of the trial, treatment assignments were reversed for another three nights. During each three-night phase, participants were required to stay up late, shortening their time in bed by 25%. Subjective daytime fatigue and sleepiness were decreased on day 1 and objective measures of alertness were improved on days 1–3 during glycine use compared with placebo, suggesting glycine may mitigate some consequences of acute sleep loss.⁹¹ Another crossover trial in 11 healthy volunteers found 3 grams of glycine within 60 minutes before bedtime on two consecutive nights improved subjective sleep quality, sleep efficiency, and daytime sleepiness; shortened objective measurements of time to fall asleep and time to enter slow-wave sleep; and improved performance on memory tests compared with placebo.⁹² A placebo-controlled crossover trial in 19 female subjects with self-reported sleep difficulties found 3 grams of glycine before bedtime for four days improved subjective measures of daytime fatigue, energy level, and clear-headedness.⁹³

Ashwagandha

Reported Dosage: 120–700 mg of ashwagandha extract daily

Ashwagandha (Withania somnifera) is used in traditional Ayurvedic medicine as a remedy for insomnia, anxiety, stress, and various other ailments, as well as to build physical and mental vitality.⁹⁴ A meta-analysis that pooled results from five randomized controlled trials found ashwagandha extract improved sleep, increased mental alertness, and decreased anxiety in healthy adults with and without insomnia.⁹⁵ In one randomized controlled trial involving 144 healthy participants with high non-restorative sleep scores, 120 mg of a standardized extract of ashwagandha root and leaf, called Shoden, daily for six weeks improved time to sleep onset, wakefulness after sleep onset, total sleep time, and sleep efficiency as measured by actigraphy. In addition, self-reported sleep quality scores improved by 72% in those treated with ashwagandha extract, but only 29% in those given placebo.⁹⁶ A randomized controlled trial that included 40 subjects with insomnia and 40 healthy subjects found eight weeks of treatment with ashwagandha improved sleep parameters more than placebo in both participant groups, although the effects were more pronounced in those with insomnia.⁹⁷ In a trial in 60 college students, 350 mg of a full-spectrum ashwagandha extract twice daily for 30 days was more effective than placebo at improving self-reported sleep quality and reducing food cravings, but not for reducing self-perceived stress levels.⁹⁸ Another report from the same trial indicated ashwagandha use also led to greater self-perceived well-being due to better energy levels, mental clarity, and sleep quality compared with placebo.⁹⁹

Black Cumin Seed Extract

Reported Dosage: 200 mg taken 20–30 minutes before bedtime

Black cumin seed (Nigella sativa) is a culinary spice and a medicinal herb. Its oil has been shown to have anti-inflammatory, oxidative stress-reducing, and neuro-protective effects.^100,101 In a randomized placebo-controlled trial that included 72 healthy subjects with self-reported non-refreshing sleep, 200 mg per day of black cumin seed oil standardized to contain 5% thymoquinone (an active compound in black cumin essential oil) for 90 days improved sleep quality and stress levels as measured by questionnaires. In addition, melatonin levels increased while cortisol (indicator of stress response activation) and orexin (neuropeptide that regulates wakefulness) levels decreased in black cumin oil-treated participants.¹⁰⁰ An uncontrolled trial that enrolled 15 healthy participants who reported poor sleep quality evaluated the same ingredient and dosage regimen for 28 days. This study found that the black cumin preparation improved scores on scales of sleep quality, anxiety, depression, and stress, and reduced blood levels of cortisol. In addition, polysomnography performed on days one and seven of the trial showed black cumin seed oil increased total sleep time, shortened time to fall asleep, decreased wakefulness after sleep onset, and improved sleep efficiency; it also increased the proportion of slow wave (deep) and REM sleep while decreasing lighter NREM sleep stages.¹⁰²

Tryptophan

Reported Dosage: 1–4.8 grams taken 20–30 minutes before bedtime

Tryptophan is an essential amino acid needed for synthesis of serotonin and melatonin.¹⁰³ Interestingly, sleep deprivation has been shown to reduce synthesis of serotonin and melatonin from tryptophan, instead favoring tryptophan breakdown into compounds that may have toxic effects in the brain.¹⁰⁴ Tryptophan and its derivative, 5-hydroxytryptophan (5-HTP), have been used to treat depression, anxiety, and sleep disorders,^103,105 and higher dietary tryptophan intake was linked to lower risk of depression and increased self-reported sleep duration in an observational study with 29,687 participants.¹⁰⁶

A crossover trial examined the effect of 1 gram of tryptophan daily for seven days compared with seven days of placebo in 98 participants with no sleep disorder diagnosis, 47 of whom had a genetic variant associated with changes in serotonin activity and increased risk of sleep impairment. Tryptophan was found to reduce wakefulness after sleep onset and increase sleep efficiency as measured with actigraphy in all participants and improve subjective sleep quality scores in those carrying the genetic variant of interest. In fact, subjective sleep quality was worse in the genetic variant group compared with the non-genetic variant group during the placebo phase, but not during the tryptophan phase.¹⁰⁷ Another placebo-controlled crossover trial by the same research group found 3 grams of tryptophan nightly for seven nights improved sleep quality scores in 57 carriers of the genetic variant of interest and high susceptibility to stress.¹⁰⁸

A meta-analysis of findings from four randomized controlled trials found tryptophan, at doses of 1 gram or more nightly, was particularly effective at improving indicators of sleep maintenance, such as decreasing wakefulness after sleep onset and increasing sleep efficiency.¹⁰⁹ In a placebo-controlled trial with 28 healthy subjects reporting no or mild sleep difficulties, taking a single dose of a protein supplement with 4.8 grams of tryptophan reduced sleepiness and increased sustained alertness the next morning compared with a low-tryptophan protein supplement.¹¹⁰ A study in 10 healthy sleepers found a single, daytime, 2.4-gram dose of tryptophan increased subjective sleepiness and shortened the time needed to fall asleep both one and two hours later.¹¹¹

Chamomile Extract

Reported Dosage: 200–400 mg twice daily

Chamomile is the common name for several daisy-like flowering plants, including German chamomile (Matricaria recutita) and Roman or English chamomile (Chamaemelum nobile), with similar medicinal properties. Chamomile extracts are widely used to support sleep, soothe tension, and relieve pain.¹¹² A meta-analysis published in 2019 assessed findings from six randomized controlled trials and concluded that chamomile improved sleep quality in people without an insomnia diagnosis.¹¹³ A similar systematic review and meta-analysis published in 2024 examined the effects of chamomile on sleep quality across 10 clinical trials with 772 participants. The included studies used a variety of forms and dosages of chamomile preparations, including extract capsules, teas, and drops. The results showed that, in five of the studies that could be pooled and analyzed together, chamomile significantly improved PSQI scores, reflecting better overall sleep quality. However, it did not consistently improve sleep duration or efficiency. Chamomile helped with sleep onset latency in three of four studies, and reduced the number of awakenings during the night in two of three studies, though it did not affect daytime functioning. One randomized controlled trial involving 60 subjects aged 60 years and older found baseline sleep quality, based on PSQI scores, among participants was poor and improved more in those receiving 200 mg chamomile extract twice daily for 28 days than placebo.¹¹⁴ Another trial in 77 older individuals living in nursing homes found 400 mg chamomile twice daily for four weeks improved sleep quality scores compared with no treatment.¹¹⁵ In a randomized controlled trial that included 80 women who had recently given birth and were experiencing poor sleep quality, sleep quality scores improved after two weeks in women instructed to drink chamomile tea.^116,117

Theanine

Reported Dosage: 50–400 mg daily OR 200 mg taken before bedtime

Theanine is an amino acid found in green tea (Camellia sinensis). Theanine is not used for protein synthesis, but has many health benefits related to its free radical-scavenging, anti-inflammatory, immune-modulating, and calming effects.¹¹⁸ Clinical research has indicated theanine may support healthy sleep by relieving anxiety rather than inducing drowsiness.¹¹⁹

In a randomized, controlled, crossover trial in 30 healthy adults with stress-related symptoms, self-reported sleep parameters including time needed to fall asleep, sleep disturbance, and sleep medication use improved after four weeks of taking 200 mg theanine nightly compared with placebo.¹²⁰ In a placebo-controlled trial involving 20 university students going through a period of increased stress, 200 mg theanine twice daily for 17 days lowered salivary levels of a marker of stress; and lower levels of this stress marker were correlated with longer sleep duration.¹²¹ In a trial in nine healthy young women, 50 mg theanine reversed the negative effects of caffeine on wakefulness after sleep onset.¹²²

Vitamin D

Reported Dosage: 25–125 mcg (1,000–5,000 IU) daily. Note: vitamin D supplementation dosage should be based on 25-hydroxyvitamin D blood levels.

Vitamin D appears to play a role in serotonin and melatonin regulation, and low vitamin D status has been linked to poor sleep in some, but not all, observational studies.¹²³ In a study that evaluated data from a representative sample of 4,913 U.S. adults derived from the 2011–2016 National Health and Nutrition Examination Survey (NHANES) cohort, higher vitamin D concentrations were associated with a lower likelihood of sleep disorders. The researchers also used a genetic research method called Mendelian randomization (which helps study whether an outcome is caused by a certain trait) and found that vitamin D might be causally linked to sleep disorders.¹²⁴ Several additional observational studies suggest a potential link between vitamin D deficiency and sleep problems.^125-127 Interestingly, some evidence suggests relationships between vitamin D deficiency and higher risks of heart disease and cognitive dysfunction may be due in part to abnormal sleep patterns and poor sleep quality.^128-130

A systematic review of 19 clinical trials, three of which were pooled in a meta-analysis, found vitamin D supplementation improved subjective sleep quality.¹³¹ A prospective cohort study evaluated the effects of vitamin D supplementation in 152 active-duty soldiers stationed in the U.S. Pacific Northwest. Participants with low serum vitamin D levels received either 25 mcg (1,000 IU) per day or 125 mcg (5,000 IU) per day of vitamin D3 for three months. Participants whose vitamin D levels were not low at baseline did not receive vitamin D supplements. Sleep quality was assessed with a validated patient-reported survey. Subject-reported sleep was improved in the vitamin D-treated groups after three months.¹³² A small, uncontrolled case series involving 28 U.S. veterans similarly concluded that increasing vitamin D status through supplementation improved subjective sleep quality compared with baseline. Participants in this study were supplemented with 30 mcg (1,200 IU) vitamin D daily if serum 25-hydroxyvitamin D was between 20 and 29 ng/mL or 1,250 mcg (50,000 IU) weekly if serum 25-hydroxyvitamin D was below 20 ng/mL.¹³³

Saffron Extract

Reported Dosage: 14–28 mg, taken one hour before bedtime OR 7.5 mg crocetin taken after the evening meal

Saffron (Crocus sativus) is a well-known culinary herb, and a number of clinical trials have indicated saffron can improve mood and sleep.¹³⁴ A randomized placebo-controlled trial in 120 subjects who described their sleep as unsatisfactory found treatment with 14 mg or 28 mg of a standardized saffron extract, taken one hour before bedtime for 28 days, improved subjective sleep quality and mood scores.¹³⁵ Similarly, a trial in 63 healthy adults with self-reported sleep problems found 14 mg saffron extract twice daily for 28 days led to greater improvement in sleep quality scores than placebo.¹³⁶ In a randomized controlled trial in 66 participants with mild-to-moderate sleep disorders related to anxiety, subjective measures of time needed to fall asleep, sleep duration, and sleep quality improved in those given 15.5 mg saffron extract daily for six weeks, but not in those given placebo.¹³⁷ A randomized, placebo-controlled, crossover trial involving 30 subjects with mild sleep complaints found 14 days of treatment with 7.5 mg crocetin, a compound extracted from saffron, increased the intensity of sleep drive as measured with EEG; subjective measures showed crocetin also reduced feelings of sleepiness and increased feeling refreshed in the morning.¹³⁸ Saffron has also been found to be beneficial for insomnia disorder.¹³⁹

Probiotics

Reported Dosage: Highly variable. Since there are many probiotic strains available, it may be reasonable for most people to try a few different options with the overall goal in mind of supporting gut and overall health, as doing so may be linked to better sleep.

The gut microbiome is tightly interconnected with the nervous system. An imbalance in gut bacteria and metabolites can alter levels of neurotransmitters involved in central sleep-wake regulation, possibly contributing to sleep problems.¹⁴⁰ Conversely, poor sleep can change the composition of the gut microbiome, which may contribute to metabolic disturbance and immune, neurologic, and hormonal dysregulation.^141-143

A growing body of research indicates probiotics and related supplements can play a role in supporting healthy sleep. Many randomized placebo-controlled trials in healthy adults have shown a range of probiotic strains and dosages can improve sleep quality.^144-154 Although it is challenging to synthesize the evidence due to the range of species and formulations used, a meta-analysis of data from 20 clinical trials found treatment with probiotics, killed probiotics, or cellular parts of probiotics improved subjective sleep quality in general, but did not affect objective measures of sleep. The benefits appeared to be slightly stronger in healthy individuals (rather than those with medical problems), when single organisms were used (rather than combinations), and when the treatment duration was eight weeks or longer.¹⁵⁵ Another meta-analysis included findings from six placebo-controlled trials that used heat-killed or lyophilized (freeze-dried) Lactobacillus gasseri CP2305 alone in healthy adults with mild-to-moderate stress; the analysis found this strain of L. gasseri improved subjective sleep quality, as well as objective sleep parameters in the two trials that included EEG measurements.¹⁵⁶

On the other hand, a meta-analysis of 18 randomized controlled trials found supplementing with probiotics and/or prebiotics (fibers that enhance growth of beneficial bacterial colonies in the gut) had no effect on sleep quality or duration.¹⁵⁷

Hops

Reported Dosage: 400 mg of hops extract taken in the evening. Some studies evaluated non-alcoholic beer consumption as a source of hops, although the hops dosage is variable in this context.

Hops, the flower cones from the hop (Humulus lupus) plant, are used as a flavoring agent in beer and have well-known sedative effects. Extracts from hops have been shown to increase gamma aminobutyric acid (GABA) receptor activity, reducing excitability of the nervous system and supporting the onset of sleep.^158,159 A randomized, placebo-controlled, double-blind, crossover study assessed the effects of a branded hops dry extract, called Melcalin Hops, on self-reported depression, anxiety, and stress levels in 36 healthy young adults with mild symptoms. Participants received two 200 mg capsules of the hops extract or placebo daily for four weeks, separated by a 2-week washout period. The study found that hops supplementation significantly reduced depression, anxiety, and stress scores compared to placebo, with no changes in cortisol levels or body composition.¹⁶⁰ Although this study did not assess sleep outcomes, the improvements in some self-reported mood problems like stress and anxiety suggest that hops extract may provide some benefit for sleep.

In a pilot trial with 97 healthy participants, drinking non-alcoholic beer providing 35 mg of hop bitter acids nightly for three weeks resulted in improved subjective assessments of sleep quality; job performance; and mood, including anxiety, depression, fatigue, and vigor.¹⁶¹ In another trial, 30 healthy university students reported shorter time to sleep onset and better overall sleep quality after having a hop-containing non-alcoholic beer with dinner nightly for two weeks compared with the week before they had the beer.¹⁶² A trial in 17 healthy female nurses working rotating or night shifts found drinking 333 mL (about 12 ounces) of a hoppy non-alcoholic beer nightly for two weeks resulted in shorter time to fall asleep and better sleep quality as assessed by actigraphy.^160,163

Hops are often used in conjunction with other herbs and nutrients to support healthy sleep. For example, in a placebo controlled trial in 40 subjects with poor sleep, a single dose of a combination of valerian and hops was found to improve subjective and objective measures of sleep quality, including total sleep time and time in deep sleep.¹⁶⁴

Valerian

Reported Dosage: 200–1,215 mg of extract daily; some studies reported 600 mg of extract taken one hour before bedtime

Valerian (Valeriana officinalis) is a medicinal plant that is commonly used to promote sleep. A meta-analysis of 10 randomized controlled trials showed valerian improved sleep quality, and the effect was more consistent when the whole valerian root, rather than extract, was used.¹⁶⁵ A study published in 2023 evaluated the effects of a standardized Valeriana officinalis extract called Sleeproot on sleep quality in individuals with mild insomnia. Over eight weeks, 80 adults were randomized to receive either the extract or a placebo. Participants randomized to valerian took 200 mg of the extract, standardized to contain 2% total valerenic acid, daily. They were instructed to take one capsule one hour before bedtime for the duration of the eight-week study with sleep improvements tracked through both a subjective questionnaire (PSQI) and objective measures (wrist actigraphy and polysomnography). Participants in the valerian group showed significant improvements in sleep latency, total sleep time, sleep efficiency, reduced anxiety, and reduced daytime sleepiness compared with placebo. By the end of the study, those in the valerian group also reported feeling more refreshed upon waking.¹⁶⁶ Another placebo-controlled trial in 14 elderly participants with self-reported poor sleep found 405 mg valerian extract three times daily for seven days increased slow-wave sleep as assessed with polysomnography.¹⁶⁷ Another trial in 16 insomnia patients found 600 mg valerian extract nightly increased both slow-wave and REM sleep while decreasing N1 sleep after two weeks of use.¹⁶⁸

A clinical trial in which 128 subjects received 400 mg valerian extract, a commercial valerian product (not otherwise described), and placebo in random order and on three non-consecutive nights found the valerian extract increased subjective sleep quality and shortened the time to fall asleep. The effect was stronger in those who self-identified as poor sleepers, reported usually taking a long time to fall asleep, and those who smoked.¹⁶⁹ Another clinical trial compared 450 mg and 900 mg valerian extract to placebo in 10 subjects who slept at home and 900 mg of valerian to placebo in eight subjects who were evaluated in a sleep lab. At home, self-reported time to fall asleep and wakefulness after sleep onset were decreased after valerian use, but sleep quality scores did not change; in the lab, valerian did not have a significant effect on sleep compared with placebo.¹⁷⁰ In a randomized placebo-controlled trial involving 102 healthy individuals, 600 mg valerian extract an hour before bedtime did not cause morning sleepiness, poor concentration, or reduced reaction time after a single use or nightly use for two weeks, confirming the safety of valerian in healthy people.¹⁷¹

Cherry Products (Tart Cherry & Sweet Cherry)

Reported Dosage:

• Tart Cherry: 200–240 mL of tart cherry juice twice daily or 30 mL of tart cherry concentrate twice daily
• Sweet cherry (Jerte Valley): 200 grams of cherries twice daily or cherry powder equivalent to about 141 grams of cherries twice daily

Both sweet and tart cherries are rich in vitamin C and other free radical-scavenging compounds, and tart cherries are good sources of tryptophan, serotonin, and melatonin.¹⁷² Findings regarding the effects of tart cherry on sleep parameters have been mixed. In a randomized placebo-controlled trial in 20 healthy volunteers, tart cherry juice consumption for seven days increased melatonin levels, as well as time in bed, sleep duration, and sleep efficiency.¹⁷³ A trial that included 19 healthy field hockey players whose sleep was monitored by actigraphy found 200 mL (about 7 ounces) of tart cherry juice (equivalent to about 48 tart cherries), taken five times during a 48-hour period, resulted in increased time in bed, decreased wakefulness after sleep onset, and reduced nighttime movement compared with placebo juice consumption.¹⁷⁴ However, in a trial in which 44 healthy subjects received either 240 mL (8 ounces) of tart cherry juice, placebo juice, encapsulated tart cherry powder, or placebo capsules twice daily for 30 days, no differences in sleep parameters were found between the tart cherry and placebo groups.¹⁷⁵ In addition, a randomized controlled trial in 50 healthy middle-aged adults found 30 mL of tart cherry juice concentrate twice daily for three months increased alertness, decreased fatigue, and improved sustained attention during a cognitive task, but did not affect sleep compared with placebo.¹⁷⁶

Two clinical trials by one research group have investigated the effect of sweet Jerte Valley cherries on sleep. In one trial, six middle-aged and six elderly healthy volunteers added 200 grams (about 7 ounces) of cherries twice daily to their usual diet. Seven regional cherry varieties were tested for three days each. Cherry consumption increased melatonin levels as well as sleep duration and inhibited movement during sleep as measured by actigraphy.¹⁷⁷ In the other trial, 10 young, 10 middle-aged, and 10 elderly healthy subjects consumed a cherry powder product equivalent to 141 grams of cherries or placebo twice daily for three days. Actigraphy testing showed cherry powder improved time to fall asleep, number of awakenings, sleep efficiency and duration, and nighttime movement, and the effect on sleep was stronger in older subjects.¹⁷⁸

Bioactive Milk Peptides

Reported dosage: 150–300 mg of milk protein hydrolysate

Hydrolysis of the milk protein casein generates bioactive peptides (small amino acid chains), including some that have been studied for their effects on mood and sleep. For example, a hydrolyzed milk protein known as casein tryptic hydrolysate has been found to prolong sleep duration in mice.¹⁷⁹ In preclinical research, alpha-casozepine, a 10-amino acid peptide derived from casein tryptic hydrolysate, has been found to sensitize GABA receptors and relieve anxiety related to stress without triggering dependence.¹⁸⁰

A randomized, double-blind, placebo-controlled trial investigated the effects of a branded alpha-casozepine called Lactium on sleep difficulties in Japanese adults. The study involved 32 participants who received either the casein hydrolysate (150 mg daily for four weeks) or a placebo. The casein hydrolysate significantly improved subjective sleep quality.¹⁸¹

In another study, 43 Korean adults with mild-to-moderate sleep problems took either 300 mg of Lactium or a placebo every day for four weeks. Participants then underwent a four-week washout period and switched to the other treatment for four additional weeks. Although standard sleep quality tests did not show substantial differences between treatments, subjective sleep diaries revealed that Lactium supplementation led to greater total sleep duration, shorter time to fall asleep, and fewer wake-ups.¹⁸²

In a different study, 40 adults with sleep problems took either a placebo or a combination of 300 mg Lactium and 204 mg L-theanine (an amino acid from tea with relaxing properties) daily for eight weeks. While there were no significant differences between the groups on sleep quality and insomnia scale characteristics, self-reported sleep diaries revealed that the group taking the Lactium-theanine combination slept longer, fell asleep faster, had fewer wake-ups, and went to bed earlier. The researchers also found changes in the beneficial bacteria in the gut of those who took the supplement.¹⁸³ Another trial in 39 subjects with poor sleep quality scores found a branded supplement containing 150 mg of casein tryptic hydrolysate plus 50 mg theanine nightly for four weeks improved self-reported sleep duration, sleep efficiency, daytime dysfunction, and overall sleep quality scores more than placebo.¹⁸⁴

Diet

Both the timing and composition of meals can profoundly impact the function of the internal circadian clock and regulation of sleep. Nutrients and nutrient metabolites can directly alter nervous system signaling related to sleep health. In addition, diet can trigger inflammatory processes that may lead to dysfunction in the nervous system and other body systems that may ultimately harm sleep.^185,186

Chrono-Nutrition: Eating for Circadian Health

Eating has a close and circular relationship with the body’s internal circadian system. Normal circadian rhythms drive healthy appetite, digestive function, and metabolic processes during the daytime, while sleep loss can trigger abnormal appetite patterns and nutrient metabolism that, over time, can contribute to digestive and metabolic diseases.¹⁸⁷ On the other hand, poor eating habits, digestive problems, and metabolic disorders can disrupt gut microbial balance and circadian synchrony, potentially triggering sleep disorders.^186,188

Chrono-nutrition is a strategy to align eating with circadian systems in order to take advantage of optimal digestive and metabolic activity and support sleep health.¹⁸⁶ Guidelines include¹⁸⁶:

• Eat the majority of the day’s calories in the daytime (rather than at night). Eating most of the day’s calories at night has been associated with poor sleep quantity and quality, chronic insomnia, unhealthy eating behaviors, and metabolic health problems.^187,189
• Avoid eating and drinking within two hours of bedtime. Observational studies have found eating and drinking close to bedtime was correlated with increased wakefulness and increased chance of abnormal (short or long) sleep duration.^190,191
• If you need to snack at night, choose small portions of unprocessed foods. While eating close to bedtime is generally not advised, a carefully chosen bedtime snack may be helpful for avoiding nighttime hunger in some circumstances, especially in individuals prone to low blood glucose levels during the night.¹⁹² Low-calorie, nutrient-dense, simple snacks (rather than complex meals) do not appear to harm sleep parameters and may be beneficial for metabolic health in some individuals.^193-196 Examples of good bedtime snacks include small portions of fruit, unsalted nuts, unsweetened yogurt, or a protein drink.¹⁹⁷
• Stick to consistent mealtimes, ideally three times per day. Fewer meals and more frequent snacking, especially at night, has been associated with shorter sleep duration.¹⁹⁸

Dietary Patterns

Getting too little sleep has consistently been shown to be linked to poor eating habits, including eating too many calories, too much fat, and too little fruit, as well as a shift away from three meals a day to smaller, more frequent, high-calorie snacks, especially at night.¹⁹⁸ On the other hand, a healthy diet is essential to optimal circadian function, and nutrient imbalance may contribute to poor sleep.^199-201 Dietary patterns that support cardiovascular, metabolic, and overall health, such as a Mediterranean diet and Dietary Approaches to Stop Hypertension (DASH), have also been found to be associated with high sleep quality in most observational studies.^199,202-204 For example, in a study that scored adherence to a Mediterranean diet in 1,031 adults in Turkey under 65 years of age, a higher Mediterranean diet score was correlated with higher sleep quantity and quality.²⁰⁵

A plant-based diet is often considered to be healthful, but not all plant-based eaters consume high amounts of whole, nutrient-dense, unprocessed foods. In a study in 2,424 middle-aged and older adults in China, eating a healthy plant-based diet (eg, generally a Mediterranean-style diet rich in plant fibers, whole grains, vegetables, and minimally processed food) was associated with better sleep quality, while eating an unhealthy plant-based diet (ie, highly processed) was linked to poorer sleep quality.^206,207

Diet Composition

The composition of the daily diet may affect sleep patterns. Several clinical trials have indicated high-carbohydrate diets may shorten the time needed to fall asleep and periods of wakefulness, and increased fiber in the diet may increase deep slow-wave sleep.²⁰⁸ One crossover trial that compared a high-protein diet to a high-carbohydrate diet in 24 healthy men found the high-carbohydrate diet led to a small increase in melatonin production, less time in light (N1) sleep, less time needed to fall asleep, and better sleep efficiency compared with the high-protein diet.²⁰⁹ On the other hand, meta-analyses of clinical trials have found a low-carbohydrate diet increased the length and proportion of slow-wave sleep, decreased REM sleep, reduced time to sleep onset, and increased sleep efficiency.^210,211 The quality of carbohydrates in the diet are also important to consider, since a diet rich in fiber-dense carbohydrates may promote optimal sleep through a range of mechanisms.²¹²

Ketogenic diets are very low in carbohydrate, high in fat, and adequate in protein, and are used to treat epilepsy and obesity. People following this diet generate large amounts of ketone bodies, byproducts of fat metabolism made in excess when glucose levels are very low. Ketogenic diets have been found to reduce appetite and food intake and may improve sleep quality, although the data on sleep is inconclusive.²¹³ A clinical trial in 324 women with overweight and obesity found adhering to a very low-calorie ketogenic diet for 31 days led to improved subjective sleep quality, and sleep improvement was associated with the degree of body fat loss.²¹⁴ Emerging evidence suggests ketone bodies may alter circadian signals affecting appetite and the sleep-wake cycle.^213,215

One study examined the diets of 15,991 Americans and scored them based on the balance of pro-oxidants (foods high in iron, omega-6 fatty acids, and saturated fat) and antioxidants (foods high in carotenes and carotenoids, selenium, vitamins C and E, and omega-3 fatty acids). After following the participants for a median of 7.4 years, those with short sleep duration and a balance favoring dietary antioxidants were found to have a lower mortality rate than short sleepers with a pro-oxidant-favoring diet.²⁰⁷ Another study that used data from 6,300 participants in the NHANES found a higher antioxidant to pro-oxidant balance was correlated with longer sleep duration and lower risk of sleep disorders.²¹⁶ These findings suggest eating an antioxidant-rich diet may not only increase sleep duration but may also protect against some of the negative health effects of short sleep.

Specific Foods

Certain specific foods have been linked to better sleep. For example, studies have shown milk, tart cherries, kiwis, and fatty fish are foods that can promote sleep.^186,217 This may be partly due to their natural melatonin content. Other food sources of melatonin include eggs, wheat, oats, grapes, strawberries, peppers, tomatoes, and mushrooms.²¹⁷

Other foods and beverages can worsen sleep.¹⁸⁶ For example, alcohol is a nervous system depressant and can shorten the time needed to fall asleep. Although many individuals use alcohol to help them fall asleep, it can also alter sleep architecture and interfere with circadian rhythms, increasing the risk of sleep problems.²¹⁸ Furthermore, in animal research, intermediate and heavy alcohol intakes were found to temporarily but dramatically suppress glymphatic function, potentially leading to brain cell damage, whereas light alcohol intake was shown to increase glymphatic clearance.²¹⁹

Nicotine is another important consideration: though not found in significant amounts in food, nicotine has complex effects on neurotransmitter activity and negatively impacts sleep. Nicotine in tobacco products can lengthen the time needed to fall asleep, decrease sleep efficiency, increase sleep fragmentation, and reduce sleep quality.¹⁸⁶ Limiting or avoiding alcohol and nicotine, especially in the four hours prior to bedtime, may help optimize sleep.^218,220

A growing body of research shows several key lifestyle factors are associated with better sleep quantity and quality. Adopting these sleep-promoting habits may help individuals live healthier and more vibrant lives. It is also important to identify and treat or modify any obstacles to healthy sleep that may be present, such as an undiagnosed sleep disorder, a mental health disorder, or use of a medication that can harm sleep.

Check for Undiagnosed Sleep Disorders

Many common sleep disorders go unrecognized, undiagnosed, and untreated.²²⁶ Common sleep disorders, which frequently co-occur, include:

• Chronic insomnia (lasting three months or longer) is estimated to affect about 10% of the population.^227,228
• Obstructive sleep apnea (frequent bouts of airway narrowing or collapse, breathing interruption [apnea], and waking during sleep) affects an estimated 10% of the population.^227,229
• Sleep bruxism (jaw clenching and teeth grinding during sleep) affects up to 15% of adults and as many as 49% of children.²³⁰
• Restless legs syndrome (muscle restlessness with a desire to move the limbs, especially at night) is estimated to affect 3% of the general population, with higher prevalence in women and older individuals.²³¹

Nocturia (waking at night to urinate) can contribute to poor sleep quality and often coexists with chronic insomnia disorder, especially in older individuals.^232,233 Nocturia is the most common cause of sleep interruption in elderly adults, and may be attributable to changes in hormone balance, bladder capacity, and circadian function.^234-236 Waking to urinate two or more times per night has been associated with lower subjective sense of well-being, lower workplace performance, and poorer general health status.^237-239

Sleep disorders occur more frequently in individuals with neurological, psychiatric, and other health problems; in turn, chronic sleep disturbance is correlated with increased risks of a range of health problems, including cardiovascular, metabolic, neurologic, and psychiatric conditions, as well as frailty and mortality.^2,240,241 If you suffer from frequent poor sleep, it is important to consult a health care provider to investigate the possibility of a sleep disorder and initiate treatment if appropriate.

More information about sleep disorders can be found in Life Extension’s Insomnia, Sleep Apnea, and Restless Legs Syndrome protocols.

Check for Depression, Anxiety, & Stress

Sleep has a bi-directional relationship with mental health, such that chronic sleep disorders increase the risks of depression, anxiety, and related disorders, while in turn mental health disorders increase the risk of sleep disorders.^242-244 Even occasional bouts of poor sleep have a negative impact on mood and may increase the risk of developing anxiety disorder, depression, and exhaustion syndrome.²⁴² Interestingly, in one study that included 115 participants with insomnia, lower scores on subjective assessments of sleep quality and “morningness” (seeing oneself as a “morning person”) were more closely associated with depressive symptoms than objective sleep studies (polysomnography) or measures of circadian clock type.²⁴⁵

Sleep loss is known to activate the body’s stress signaling network, which can further aggravate sleep disruption.²⁴⁶ Prolonged stress and burnout have been shown to impair sleep quality, and those affected by short-term and long-term sleep disturbances have reported higher levels of stress and burnout.^242,243 For example, one study that followed 59 medical students for 90 days found subjective measures of work-related stress were higher on workdays following nights with low sleep duration.²⁴⁷ The relationship between poor sleep and a dysregulated stress response has been proposed as an underlying mechanism by which sleep loss contributes to physical and mental health problems.¹⁶ Chronic stress signaling even appears to inhibit glymphatic function, leading to a buildup of neurotoxins that may contribute to neurologic disorders.³⁰ On the other hand, restoring sleep health is an important part of treatment for mental health disorders through its ability to regulate stress signaling, reduce brain inflammation, and improve neuroplasticity.^16,244

Treating underlying depressive and anxiety disorders and managing stress effectively can be helpful for improving sleep. More information about these conditions can be found in Life Extension’s Depression and Depressive Disorders, Anxiety and Anxiety Disorders, and Stress Management protocols.

Are Medications Disrupting Your Sleep?

Drug prescriptions and the regular use of multiple medications at the same time have increased substantially over the past two decades. As of 2016, approximately 17% of Americans were using at least one medication with insomnia as a potential side effect, and about 7% were using two or more such drugs.²⁴⁸

A wide range of drugs may interfere with sleep in susceptible individuals. Some commonly prescribed examples include:

• Thyroid medications, such as levothyroxine (Synthroid)²⁴⁸
• Antidepressants and anti-anxiety drugs, such selective serotonin reuptake inhibitors (SSRIs) like fluoxetine (Prozac), citalopram (Celexa), and escitalopram (Lexapro); and serotonin norepinephrine reuptake inhibitors (SNRIs) like venlafaxine (Effexor), duloxetine (Cymbalta), and desvenlafaxine (Pristiq)^248,249
• Stimulants (ie, a class of drugs usually used to treat attention deficit disorder), such as methylphenidate (Ritalin) and amphetamine-dextroamphetamine (Adderall)²⁴⁸
• Sedatives, such as diazepam (Valium) and triazolam (Halcion)²⁵⁰
• Drugs used to treat cognitive disorders, such as donepezil (Aricept), rivastigmine (Exelon), and galantamine (Razadyne)^251-253
• Cold medications, particularly pseudoephedrine (Sudafed) and combination products with pseudoephedrine²⁴⁸
• Glucocorticoids, such as prednisone (Deltasone), dexamethasone (Decadron), and methylprednisolone (Medrol)^254,255
• Smoking cessation therapies, such as varenicline (Champix), bupropion (Zyban), and nicotine replacement patches (Nicoderm), lozenges (Nicorette), and gum (Nicorette)²⁴⁸
• Opioid pain relievers, such as morphine (MS-Contin and others), tramadol (Ultram), oxycodone (Oxycontin), hydrocodone/acetaminophen (Vicodin), oxymorphone (Opana), and fentanyl (Duragesic)^248,256
• Some asthma medications, eg, theophylline (Elixophyllin and others) and albuterol (Ventolin and others)²⁵⁷
• Some blood pressure-lowering drugs, eg, beta-blockers like atenolol (Tenormin) and metoprolol (Lopressor)^258,259

Although sedatives in the drug class called benzodiazepines, including diazepam (Valium), alprazolam (Xanax), lorazepam (Ativan), and clonazepam (Klonopin), are frequently used to treat insomnia and anxiety, their use can disrupt normal sleep architecture by increasing time in N2 sleep and reducing restorative N3 slow-wave sleep and REM sleep.²⁶⁰ A study in two healthy subjects showed their use can suppress melatonin production.²⁶¹ Benzodiazepines are also well known to cause tolerance (the need for increasing doses to experience the same effect) and addiction with potentially life-threatening consequences. Because of these problems, benzodiazepines are only indicated for short-term use, although many people remain on them for years or even decades.²⁶²

If you are experiencing difficulty sleeping and are using one or more of the drugs listed above, speak with your health care provider before making any changes in your medication regimen.

Optimize Sleep Hygiene

Sleep hygiene is a general term for bedtime habits that enhance sleep. The components of sleep hygiene recommendations vary, but there are some consistent themes^273,274:

Avoid arousing and emotionally charged activities before bedtime. An anxious state of mind, or hyperarousal, is considered a key factor in insomnia.²⁷⁵ In addition to setting aside emotional topics in the evening, creating a to-do list for the next day before going to sleep may be a useful strategy for letting go of worry and getting good sleep.²⁷⁶

Have consistent routines around bedtime, including timing and rituals. Adhering to a structured sleep schedule with set sleep and wake times has been found to improve circadian alignment in healthy young adults, which may help optimize sleep.²⁷⁷ Social jetlag, a term that refers to the difference between sleep timing that is adjusted for socially necessary schedules (eg, during the work or school week) and natural sleep timing (eg, on the weekend when there are no social pressures), can be a cause of sleep loss and has been linked to negative health outcomes.^278-280 Although consistent earlier and less variable bedtimes have been associated with better health, it may be possible to partially mitigate the negative effects of sleep time variability and social jetlag through “catch-up” sleep, such as sleeping longer on the weekends.^280,281

Avoid smoking or drinking alcohol before bed; keep nighttime snacks early, small, and simple; and hydrate with water early in the night. Nighttime nicotine and alcohol use can diminish sleep quality.¹⁸⁶ In addition, eating or drinking close to bedtime has been correlated with increased wakefulness and higher likelihood of short or long sleep duration.¹⁹¹ However, it may sometimes be appropriate or even beneficial to eat a light simple snack before bedtime.^193,282 Good choices include foods and drinks shown to improve sleep like tart cherry juice, kiwi fruit, or a small glass of milk.²⁸³

Create a bedroom environment that supports sleep, with attention to factors such as comfortable bed and bedding, as well as ambient temperature, air quality, noise level, and light. Higher ambient temperature and increased levels of noise, carbon dioxide, particulate pollution, and light pollution have all been associated with worse sleep quality in healthy adults.^284,285

• Comfortable bed. While bed preferences vary between individuals, a medium-firm mattress has generally been found to provide the most comfort, reduce the risk of back pain, and support optimal sleep quality.²⁸⁶ Weighted blankets are sometimes promoted for their calming effect, and clinical evidence indicates they may be especially helpful in adults and children with attention deficit hyperactivity disorder (ADHD) and/or autism spectrum disorder.^287-289 An uncontrolled clinical trial in 68 elderly nursing home residents found the use of a weighted blanket improved sleep, cognitive function, and overall health and quality of life.²⁹⁰ Other research suggests their use may increase melatonin production.²⁹¹
• Temperature. An overly warm air temperature, especially combined with humidity, may interfere with natural nighttime body cooling, disrupt normal sleep architecture, and reduce sleep quality.^284,292 Some recommendations suggest an ideal sleep temperature range of 60–68ºF.^293,294 On the other hand, warming the feet by using a warm foot bath before bed or socks in bed has been shown to further improve sleep health.²⁹⁵
• Air quality. Using a bedroom air purifier and opening a bedroom window or door are strategies that have been found to reduce carbon dioxide and particulate levels and improve objective and subjective sleep measurements.^296,297
• Noise. Noisy neighborhoods and traffic noise have been linked to poor sleep and negative health outcomes, with shorter sleep duration, increased sleep fragmentation, lower sleep efficiency, and greater daytime sleepiness.^285,298 Earplugs and white (background) noise generators may help reduce the effects of noise on sleep, but findings from clinical trials are inconclusive.^299,300
• Light. Exposure to artificial light at night can suppress melatonin release, disrupting circadian processes and making it harder to fall asleep.²⁸⁵ Moreover, exposure to light at night has been shown to be associated with a host of health problems beyond just sleep issues.^301,302 Eye masks are a simple strategy for reducing nighttime light exposure and have been shown to lengthen slow-wave deep sleep and improve alertness and cognitive function the next day in healthy young adults.³⁰³ Anecdotally, “blackout” or light-blocking curtains may be helpful.

Get plenty of exercise during the day. Regular daytime exercise has consistently been shown to improve subjective sleep quality and reduce health risks associated with poor sleep.^304-306 Animal research also suggests exercise may protect against neural injury that could contribute to poor sleep by strengthening glymphatic activity.^307,308 Because of its powerful effects, regular exercise is an important component of sleep hygiene programs; however, avoiding strenuous physical activity close to bedtime is frequently advised. Meta-analyses of clinical trials have shown high-intensity exercise in the hour before bedtime reduced REM sleep, increased the time needed to fall asleep, and reduced sleep duration and sleep efficiency in healthy young and middle-aged adults; but these negative effects were not seen with light- and moderate-intensity exercise or when exercise occurred two to four hours before bedtime.^309-311

Spend time in sunlight. Time in the sun is important for maintaining healthy circadian function and has been found to be associated with better sleep.³¹² A growing body of evidence suggests getting adequate sunlight, whether outdoors or through windows, during the day may be more important than artificial light exposure at night for circadian and sleep health.^312,313 Of course, skin protection or sunscreen should be used during extended exposure to direct outdoor sunlight.

Avoid screen-time in bed or around bedtime. The use of light-emitting devices such as televisions, computers, and smartphones near bedtime has been linked to difficulty falling asleep, staying asleep, and worse sleep quality. One reason may be the light-emitting diodes (LEDs) in these devices, which generate light that is enriched in blue light. Light receptors in the circadian system are especially sensitive to blue light, which suppresses melatonin secretion and increases alertness.³¹⁴ Despite the popularity of blue light-blocking filters and glasses, there is limited evidence for their ability to improve sleep in nighttime users of digital devices.^314-316 Another factor may be social media engagement through screen time (social media may also fall under the “arousing and emotionally charged activities” category). Excessive use of social media has complex effects on the nervous system that lead to sleep loss and can trigger digital addiction in both adolescents and adults.^317-319

Engage in relaxing activities before bed. Findings from multiple studies indicate relaxing activities like mindfulness and other forms of meditation, breathing exercises, and progressive muscle relaxation may lead to better sleep quality.^320,321 Specialized apps that guide the user in mindfulness meditation and deep breathing, such as Headspace and Calm, are widely used to reduce stress and enhance sleep, and preliminary findings from clinical trials suggest they may be effective.^322,323 Music has been used for centuries as a method of enhancing relaxation and treating sleep problems, and modern clinical trials have found music-assisted relaxation can improve subjective measures of sleep quality.^324,325 Mind-body exercise like yoga, tai chi, and qigong may also support healthy sleep. One meta-analysis found mind-body exercise at least three times per week increased subjective sleep quality in older adults with sleep difficulties.³²⁶ A warm (not hot) shower or bath may also be conducive to sound sleep. One meta-analysis of 13 clinical trials found a warm shower or bath one to two hours before bedtime for as little as 10 minutes significantly shortened the time needed to fall asleep and improved self-reported sleep quality and sleep efficiency.³²⁷

Remove the bedroom clock. “Clock-watching” is a common practice during periods of wakefulness in the night. Although monitoring awake time may be perceived as a way to control sleep duration, in actuality, clock-watching has been shown to heighten frustration and exacerbate insomnia.^328,329 Removing clocks and other timekeeping devices from the bedroom and developing skills for dealing with awake time in the night are key to managing short- and long-term sleep difficulties.³²⁸

What are the Most Important Recommendations?

Sleep hygiene interventions have been shown to improve sleep in young adults,^330,331 older individuals,^332,333 and athletes^334-336 with sleep difficulties. An observational study involving 300 participants without sleep disorder diagnoses evaluated the relationships between sleep hygiene practices and subjective sleep quality using the PSQI. Of 35 sleep hygiene habits studied, 18 were independently associated with worse sleep quality²⁷³:

• Worrying about falling asleep while in bed
• Inconsistent total sleep times
• Using sleep medications
• Worrying about sleep during the day
• Going to bed feeling stressed or other negative emotions
• Checking the time during the night
• Going to bed hungry
• Having no sunlight exposure or time outside during the day
• Going to bed thirsty
• Inconsistent bedtimes
• Engaging in activities other than sleep in bed
• Inconsistent wake times
• Sleeping with uncomfortable bed or pillows
• Not taking time to relax before bedtime
• Napping during the day
• Having an unpleasant conversation near bedtime
• Sleeping in a poorly ventilated bedroom
• Pondering unresolved matters before bed

Sleep hygiene for shift-workers may include slightly different recommendations. A panel of experts recently compiled a list of recommendations and considerations specifically for shift workers to optimize the quality of their sleep³³⁷:

• Prioritize sleep (consider rescheduling non-essential tasks to not cut into sleep time)
• Aim for seven to nine hours of sleep per 24 hours
• Develop a sleep schedule
• Develop a bedtime routine
• Plan your transition to days off
• Use napping, in 15- to 20-minute bouts, as a helpful tool
• When planning sleep time, remember that sleep inertia (the groggy time between ending sleep and being fully awake) impairs performance and can raise the risk of accidents
• Create a comfortable sleep environment
• Use your bed only for sleep and intimacy
• Consider whether the amount of light in the sleep environment is affecting sleep
• Consider whether caffeine intake is affecting sleep
• Consider whether nicotine consumption is affecting sleep
• Consider whether alcohol intake is affecting sleep
• Be mindful of medications that may interfere with sleep
• Consider whether nighttime hunger or fullness is affecting sleep
• Consider whether the timing of fluid intake is affecting sleep
• Engage in regular exercise
• Develop strategies for sleep problems

Breathe Well During Sleep

Breathing through the nose is important for warming, humidifying, and filtering inspired air, and the proportion of breathing that occurs through the nose (as opposed to the mouth) normally increases during sleep.³³⁸ Too much open-mouth breathing during sleep can lead to drying of mouth and throat, periodontal disease and cavities, snoring, poor sleep, and onset and worsening of sleep apnea.^339-342

Mouth taping may be an effective solution for mouth-breathers: in a clinical trial involving 20 subjects with mild sleep apnea and open-mouth breathing, taping the mouth closed at night resulted in reduced snoring and sleep apnea, with greater benefits seen in those with worse baseline symptoms.³³⁸ A single strip of medical silicone tape, placed vertically under the nose and across both lips, was used to seal the mouth closed in the study. Nasal dilation is another method of encouraging nose breathing. Nasal dilators worn in the nostrils may be more effective at reducing snoring and sleep apnea and improving subjective sleep quality than externally worn nasal strips.^343,344

Nasal congestion, whether caused by allergic or non-allergic inflammation of the nasal passages or sinuses, reduces nose breathing and can disrupt normal sleep cycle architecture and degrade sleep quality.^339,340 Furthermore, nasal congestion is a common contributor to obstructive sleep apnea and can interfere with its treatment.^339,342 If you suspect airflow through your nose and sinuses may be suboptimal, consultation with an otolaryngologist (ie, ear, nose, and throat [ENT] doctor) may be worthwhile.

Consider Lavender Aromatherapy

Lavender (Lavandula angustifolia) is an aromatic plant that has demonstrated neuroprotective effects in preclinical studies.³⁴⁵ It is usually used in aromatherapy, or inhalation therapy, and is one of the most widely used plants for treating sleep problems.³⁴⁶ Aromatherapy using lavender has been shown to be beneficial in subjects with primary sleep disorders as well as those with other conditions that can be complicated by insomnia, such as neurological, psychiatric, heart, kidney, respiratory, and metabolic diseases, as well as cancer.^346,347

Multiple randomized controlled trials have shown lavender essential oil can improve objective and subjective measures of sleep quality in people without frank sleep disorders.³⁴⁸ In a randomized controlled trial in 24 healthy Japanese women with an average age of 20 years, those who received lavender aromatherapy via skin patches worn nightly for seven nights had greater reductions in fatigue and anxiety scores and improvement in mood, but not sleep quality, compared with those given skin patches with no aroma. Interestingly, questionnaires showed 50% of the participants had previously undiagnosed sleep disorders when they enrolled in the trial.³⁴⁹ In a controlled trial in 79 college students with self-reported sleep issues, wearing a lavender-infused aromatherapy skin patch nightly for five nights enhanced the positive effects of a sleep hygiene program on sleep quality compared with a placebo skin patch, and the effect was still significant two weeks after the end of the intervention.³⁵⁰ A controlled trial in 15 students found lavender aromatherapy for five nights reduced morning sleepiness scores.³⁵¹ Another study that enrolled 80 university students found lavender oil aromatherapy for one week improved subjective measures of sleep quality and fatigue. In this study, subjects in the intervention group placed lavender-scented stones near their beds at night.³⁵² Polysomnographic testing showed exposure to lavender aroma during sleep on one night increased the amount of slow-wave deep sleep in healthy young subjects without sleep problems.^353,354 In one trial, the increase in slow-wave sleep was correlated with increased subjective next-morning vigor.³⁵⁴

Lavender aromatherapy has been found to increase blood melatonin levels in older adults.³⁵⁵ In an uncontrolled trial in 39 older subjects living in a nursing home, lavender aromatherapy for one week reduced daytime sleepiness scores.³⁵⁶ In postmenopausal women, both oral lavender and lavender aromatherapy have been found to improve sleep and relieve other menopausal symptoms.^357,358

Adopt a Healthy Sleep Posture

There does not appear to be a strong consensus on which sleep position is best for sleep quality and overall health; choosing a sleep position often comes down to what is most comfortable for the individual. There is, however, some evidence that side-sleeping may be more beneficial than other positions. A study in 13 healthy sleepers found those who showed a preference for right side-sleeping had better sleep quality, as measured by actigraphy and questionnaire, than those who showed a preference for supine (on the back) sleeping.³⁵⁹ Side-sleeping appears to promote better cleansing of brain tissue through increased glymphatic drainage.³³ Interestingly, a preliminary observational study found 45 subjects with neurodegenerative diseases (Alzheimer disease, Parkinson disease, Lewy body dementia, and other dementias) spent more time sleeping on their backs and less time on their sides when compared with 120 healthy age-matched subjects.³⁶⁰ Other research in Parkinson disease patients has indicated greater sleep time in the supine position is associated with this condition and increases with disease duration and severity.^361-363 Conversely, a supine sleep position is frequently associated with snoring and is a contributing factor in the majority of cases of sleep apnea, both of which substantially diminish sleep quality.^364,365 Many devices have been developed to discourage supine sleeping and maintain side-sleeping—from specialized pillows to objects worn on the back and devices that vibrate gently when activated.³⁶⁶ Clinical trials in sleep apnea patients suggest positional therapy using such devices can be helpful.^364,366,367 In addition, those who cannot side-sleep may benefit from simply rotating the head to a side, possibly with the help of a specialized pillow, while sleeping in a supine position.^368,369

Synchronize Your Circadian Clock

The human body’s circadian network, which consists of a central circadian “clock” in the brain and peripheral circadian regulating cells in other tissues, synchronizes biologic processes throughout the body and shapes our behaviors within the external 24-hour cycle of light and dark.^370,371

Alignment between the circadian clock and environmental and physiologic cycles—or circadian synchrony—can be disturbed by a range of common behaviors and conditions, including shiftwork, late-night social or other activities, and travel through time zones. Light and noise exposure, nighttime eating and drinking, and temperature changes during the night can also interrupt circadian synchrony.³⁷² In addition, neurologic and psychiatric disorders can cause circadian network dysfunction and sleep-wake cycle disturbance.²⁴⁰ Chronic circadian rhythm disruption has been linked to increased risks of neurologic, psychiatric, cardiovascular, metabolic, digestive, and infectious diseases, as well as some cancers and mortality.^373-376

Circadian rhythms are expressed differently between individuals, resulting in a range of chronotypes—inherent tendencies for timing of activities and sleep. A morning chronotype has a natural inclination for morning activity, an early bedtime, and rising early, while an evening chronotype performs better later in the day and prefers a later bedtime and awakening time. About 40% of adults have a chronotype that falls somewhere on the spectrum from morning to evening, but most people have a “neither” chronotype, exhibiting no circadian preferences. Observational research shows morning chronotypes are more likely to sleep well and enjoy better mental and physical health compared with evening chronotypes.³⁷⁷

Chronotype appears to have genetic and epigenetic underpinnings and varies with age and between genders.^377,378 A test called dim light melatonin onset assesses the circadian timing of melatonin release and may be used as an objective indicator of chronotype and circadian alignment, but its role in diagnosing and monitoring sleep problems is still not well understood.³⁷⁹ Adapting lifestyle habits, social activities, and work commitments to more closely match chronotype is sometimes recommended as a strategy for avoiding circadian desynchronization.³⁷⁷ On the other hand, circadian rhythms can, to some degree, be adjusted and strengthened by establishing and adhering to a regular schedule of sleep, activity, and eating.³⁸⁰

Circadian rhythm disturbances may be treatable through chronotherapy, a technique that seeks to manipulate circadian rhythms, often using morning bright light exposure to establish a healthy sleep-wake cycle and improve circadian alignment between the body’s central clock and peripheral circadian networks throughout the body.³⁸¹ Bright light therapy is sometimes combined with one day of sleep deprivation followed by several days of structured early bedtimes and waketimes. This is called triple chronotherapy and has been shown to improve sleep parameters in people with circadian rhythm disorders and those with depression and bipolar disorder.^382,383 Daytime blue light therapy is sometimes added to chronotherapy to support daytime alertness and enhance melatonin function in the evening, and may improve measures of daytime functioning and sleep quality.^381,384

Napping & Sleep Inertia

Napping is sometimes used as a way to catch up on lost sleep, yet poor sleepers are frequently warned against daytime naps based on the belief that a nap can disrupt the normal sleep-wake cycle. Although habitual napping has been correlated with negative cognitive and physical health outcomes, especially in older individuals, occasional short naps in the early afternoon may improve mental and emotional function without disrupting the sleep-wake cycle.³⁸⁵

Clinical evidence shows a nap can be safe and restorative if it is timed correctly and is not too long. An afternoon nap, especially in the context of a sleep deficit, can effectively relieve fatigue, suppress the sleep drive, and improve cognitive function for hours; however, timed too late in the afternoon, a nap could interfere with falling asleep at bedtime.³⁸⁵ A short 10- to 20-minute nap has been shown to result in an immediate increase in alertness and mental function, possibly due to the inclusion of only lighter stages of sleep^386,387; on the other hand, a two-hour nap, which is likely to include deep slow-wave sleep, is typically followed by a period of grogginess known as sleep inertia.^385,387 Sleep inertia describes the time immediately following sleep, when one is no longer asleep but is not yet fully awake. It is a state marked by sleepiness, disorientation, and decreased cognitive performance and is aggravated by sleep loss, which causes more severe and prolonged sleep inertia.³⁸⁷

Interest in at-home sleep-tracking devices has grown tremendously over the past decade. An ever-growing number and diversity of devices are currently available offering various combinations of sleep-hacking technologies.

Wearables

Wearable devices that use actigraphy to assess sleep-wake dynamics have increased in popularity and availability over the past decade. Typically worn on the wrist (like a watch) or finger (like a ring), such devices sometimes supplement information about movement with other readings such as heart rate, skin temperature, blood oxygen levels, and skin conductivity. Many devices use algorithms to synthesize collected data and provide easy-to-understand information about sleep patterns. They may also be paired with a user interface, such as on a smart phone, to administer questionnaires that add context and may increase accuracy.⁵⁸

Data from commercial wearable sleep trackers (eg, Fitbit, Apple Watch, Garmin, Whoop, Jawbone, and Polar wrist devices; Somfit forehead patch and Dreem headband; and Oura Ring) has been shown to be consistent with clinical actigraphy measurements, but also overestimates sleep and underestimates wakefulness in bed compared with polysomnography.^56,58,392 Although some products, particularly head-worn devices, claim to be able to measure sleep architecture, they have not yet been shown to accurately discern sleep stages.^56,392 The newest type of wearable sleep-tracking device is clothing, specifically pajamas, made from fabric with an embedded network of sensors. So-called “smart” pajamas can detect body position, movement, breathing rate, and heart rate. More research is needed to validate the usefulness of sleep-tracking pajamas.⁵⁶

The Oura Ring recently became eligible for coverage with pre-tax funds in health savings accounts (HSAs) and flexible spending accounts (FSAs) in the United States.³⁹³ To access HSA and FSA funds for purchasing other wearable sleep and fitness tracking devices, a letter of medical necessity from a qualified health care provider is still required as of October 2023.³⁹⁴

Nearables

Nearables are contactless devices that are placed near the user during sleep, such as on a bedside table or the mattress. Sensors placed on or under mattresses can detect motion, respiration, and pulse, while bedside devices use light and sound sensors to measure sleep parameters.^56,395 A meta-analysis included findings from 22 clinical trials attempting to validate nearable products against polysomnography. There was a high degree of variability in performance between brands, but the contactless devices, in general, were found to overestimate sleep and underestimate wakefulness, and were relatively inaccurate at identifying sleep stages. Nevertheless, the contactless devices studied, especially those using mattress-based pressure sensors, were more accurate than actigraphy for measuring time to sleep onset, wakefulness after sleep onset, total sleep time, and sleep efficiency, and performed relatively well at sleep-tracking in healthy people.³⁹⁵

Sleep-Enhancing Technology

Many sleep-tracking devices use the data they collect to develop personalized programs for sleep enhancement. For example, a smart phone app that determines an individual’s circadian rhythm won the National Sleep Foundation 2022 SleepTech Award for Sleep Health and Wellness.³⁹⁶ The app uses circadian rhythm data to determine chronotype and develop personalized recommendations regarding timing of light exposure, food, coffee, mental activity, physical activity, and sleep to improve circadian synchrony. The app is also paired with a wearable device that uses blue light therapy intended to reset the circadian rhythm.³⁹⁷ The 2021 SleepTech Award was given to a product with sleep-monitoring earbuds that measure sleep parameters.³⁹⁶ The earbuds can also deliver personalized audio that fades as the wearer falls asleep and optional white noise during sleep.³⁹⁸

How much sleep do you need by age?

Recommended sleep durations are as follows⁴¹:

• Adults
  • 7–9 hours for adults
  • 7–8 hours for older adults
• Children
  • 14–17 hours for newborns
  • 12–15 hours for infants
  • 11–14 hours for toddlers
  • 10–13 hours for preschoolers
  • 9–11 hours for school-aged children
  • 8–10 hours for teenagers

Is it better to sleep at night or in the day?

Sleeping at night is preferred over sleeping in the daytime because it synchronizes internal circadian systems with evolutionary external cues. Circadian synchrony is necessary for healthy function of all the body’s systems.^44,370

How to improve REM sleep?

Healthy sleep depends on good sleep architecture, with adequate amounts of both REM and non-REM sleep. Avoiding heavy alcohol use and taking targeted supplements such as black cumin seed oil can help increase REM sleep.^102,218

How to sleep better away from home?

Maintaining your usual sleep-wake routine and timing can help reduce the chance of disrupting healthy sleep patterns while away from home.²⁸⁰

Why it is better to sleep in the cold

The body’s temperature naturally decreases during the night, and a sleep environment that keeps the body too warm has been shown to reduce sleep quality.^284,292

Do you fall asleep faster sleeping with someone?

Compared to people who sleep alone, those who share their bed with a partner reported falling asleep more easily, being less wakeful, getting more sleep, and feeling less daytime fatigue. They also reported lower risk of sleep apnea and reduced insomnia severity.³⁹⁹ What’s more, co-sleeping has been shown to increase continuous REM sleep and synchronization of sleep architecture between sleep partners.⁴⁰⁰ However, if your partner has sleep apnea and/or snores, moves a lot during sleep, has to urinate frequently in the night, or interrupts your sleep for other reasons, your sleep quantity and quality may be compromised.⁴⁰¹

Does your body get used to a lack of sleep?

Chronic sleep loss takes a toll on all body systems, even if you get used to feeling tired all the time.¹

Can you make up for a lack of sleep?

Catching up on sleep, such as by sleeping late on weekends, appears to mitigate, though may not completely reverse, some of the negative health effects of sleep loss.^280,281

Is how long you sleep all that matters?

Getting enough sleep is a critical part of sleep health, but the quality and timing of your sleep are equally important.³⁶

Are naps a substitute for lack of sleep?

Naps can help you recover from short-term sleep loss, but chronic sleep loss disrupts the body’s internal circadian system, which cannot be resolved with daytime napping.^44,370

Does alcohol before bed improve sleep?

Alcohol before bed may make you sleepy and help you fall asleep faster, but it can also cause abnormal sleep architecture and disrupt circadian rhythms.²¹⁸

Should you stay in bed if you cannot fall asleep?

It depends. Many sleep hygiene recommendations include using the bed only for sleep and intimacy. What’s more, evidence suggests worrying about not falling asleep can actually make sleep worse.²⁷³ So, if your time awake in bed is fraught with worry, getting up for a while to do something relaxing is probably a good idea; but if you can use the time in bed for meditation or relaxation, that may be the better choice.