The September 10, 2015 issue of the journal Cell published the discovery of researchers at Boston's Brigham and Women's Hospital of an association between higher wintertime melatonin levels and a decrease in multiple sclerosis (MS) symptoms.

"The rise in the past 50 years in the incidence of autoimmune disorders has reached an epidemic proportion and cannot be accounted by genetic risk only," write authors Francisco Quintana, PhD, and colleagues. "Thus, increasing attention is being paid to environmental factors and their impact in the immune response and T cell differentiation in particular."

Acting on the finding of improvement among 139 relapsing remitting MS patients during autumn and winter, Dr Quintana and his associates investigated the effects of melatonin in a mouse model and observed an amelioration of symptoms among animals that received the hormone. In human and mouse T cells, melatonin blocked the differentiation of pathogenic Th17 cells and boosted protective Tr1 cells. "We found that melatonin has a protective effect," stated Dr Quintana who, along with Mauricio F. Farez, is a corresponding author of the report. "It dampens the immune response and helps keep the bad guys - or pathogenic T cells - at bay."

"In the future, melatonin or its derivatives may be used in MS patients after appropriate clinical trials are conducted and dosage is established," Dr Quintana predicted.

"Here, we report that melatonin, whose levels show seasonal variability, control the balance between pathogenic and regulatory T cells," the authors conclude. "Future studies should investigate the effects of melatonin on innate immune cells in MS patients and also its role in inflammatory bowel disease and other immune-mediated disorders."

Obesity is the strongest contributor to obstructive sleep apnea, a breathing disorder that occurs during sleep and causes symptoms ranging from restless sleep to low blood oxygen (hypoxemia). About 70% of people with obstructive sleep apnea are obese and about 40% of obese individuals have sleep apnea. Among individuals with BMIs over 60, the prevalence of sleep apnea is 90%. Obese individuals are more likely to suffer from night eating syndrome or sleep-related eating disorder, disorders characterized by symptoms ranging from excessive nighttime hunger to unconscious nocturnal eating. The prevalence of these eating disorders among obese persons is 6–16%, as compared to 1.5% in the general population. Narcolepsy (excessive daytime sleepiness) is also more common in obese individuals (Akinnusi 2012).

Poor sleep quality is more than just a consequence of obesity. Rather, a vicious cycle in which obesity leads to impaired sleep leads to increased appetite leads to obesity may complicate weight loss efforts for many individuals. Studies show that sleep deprivation, as can occur when one's sleep is suboptimal due to obesity-related phenomena such as sleep apnea, is associated with increased appetite (Knutson 2007). In an insightful magnetic resonance imaging experiment, researchers showed that a brain region called the anterior cingulate cortex appears to be more responsive to anticipation of food following sleep deprivation as compared to a full night of sleep. Increased neural activity in this brain region is associated with obesity, and its level of activation correlated with appetite in this study (Benedict 2012). Thus, improving sleep hygiene and ensuring that restful, restorative sleep is attained is an integral aspect of successful weight loss.