Obesity affects more than one-third of the U.S. adult population (approximately 78.6 million) and the numbers are constantly rising. Obesity is the leading cause of United States mortality, morbidity, disability, and healthcare costs. Another epidemic of the western society is sleep deprivation where over the past years, lack of sleep and low quality of sleep have become a routine. The prevalence of insomnia increases with age and affects almost 50% of adults 65 years old and older. With age, there is a decrease in the duration of sleep (less than 6 hr.), and an increase in night-time awakenings. Moreover, with age, quality of sleep declines, with a major reduction in the duration of slow wave sleep (SWS) which is not only considered as the most restorative sleep stage 1 , but is also crucial for good health. Studies have shown a strong correlation between sleep disorders and obesity. 2
Sleep disorders and obesity
Several studies have shown that sleep deprivation and chronic short sleep cause a significant increase in the levels of Ghrelin hormone that also known as “hunger hormone” (stimulates appetite), and decrease in levels of Leptin hormone (hormone that suppressive appetite and tell our brain when we are satisfied). 3 Moreover, sleep-deprived people may be too tired to exercise and craving for high-calorie, carbohydrate-rich foods such as sweets, salty snacks and starchy food. 4
Furthermore, when we are sleep deprived there are several major metabolic hormones that are adversely affected. The imbalance between these important metabolic hormones is connected to obesity and increased risk for diabetes. 2
Obesity is one of the strongest sleep apnea risk factors (sleep apnea is pauses in breathing during sleep for 10 seconds or more). Unsurprisingly, mild to moderate obesity is associated with markedly increased sleep apnea prevalence, where, in severe obesity (BMI > 40 kg/m2), the prevalence of sleep apnea is estimated to vary between 40 and 90%. 5 On the contrary, researchers also found that sleep apnea may lead to the development of diabetes and insulin resistance (Inability of the body to use insulin). 6 7
Melatonin prevents weight gain
Melatonin (sleep hormone) is a hormone produced in the brain. Normally, melatonin levels begin to rise in the mid- to late evening, remain high for most of the night, and then drop in the early morning hours. However, with age there is a decrease in melatonin production, and as a result decrease in sleep quality and sleep duration. There is increasing evidence suggesting a link between melatonin production and fats metabolism ,impaired insulin, glucose, and antioxidant capacity. 8 Furthermore, melatonin has been found to influence insulin secretion and therefore it is not surprising that night-time melatonin levels are related to night-time insulin concentrations, in patients with metabolic syndrome. 9 Melatonin administration was found to prevent weight gain, and reduce insulin and leptin resistance (a situation where the brain ignores the signals to stop eating) 10
Both external and body-produced melatonin may play a role in prevention of obesity and improving diabetes treatment outcomes.