Reprinted from Eating Disorders Review
March/April 2005 Volume 16, Number 2
©2005 Gürze Books
Inadequate sleep may be one more element in the epidemic of obesity and overweight in the U.S. When 1001 patients 18 to 91 years of age were recently evaluated, it was learned that overweight and obese patients slept less than patients with a normal body mass index (BMI, or kg/M2) (Arch Intern Med 2005;165:25).
Robert D. Verona, MD, from Eastern Virginia Medical School, Norfolk, and colleagues found that total amount of sleep varied with BMI: it deceased as BMI increased, except in the extremely obese group (BMI >40). Mean BMI was 30. Patients in the obese group slept less than patients in the overweight group but patients in the overweight groups did not sleep significantly less than patients with normal BMIs. The extremely obese patients did not have a decline in sleep and in fact slept more than the obese patients. Women slept more than men (477 minutes vs. 450 minutes). The difference in total sleep time between patients with a normal BMI and the others was 16 minutes a day, or 1.86 hours a week. Night-shift workers had 42 minutes less total sleep time.
An explanation for the connection
Restricted sleep and obesity could be associated for several reasons. Bidirectional communication pathways exist between the brain and the cytokine-immune-endocrine systems (Sleep Med Rev 1999; 3(3):219). Cytokines, signaling molecule messengers of the immune system, can affect sleep and food intake, and have been implicated in depression, autism, and obsessive-compulsive disorder. Also, insufficient sleep can cause “peripheral effects” that may increase the risk for obesity.
According to the authors, obesity itself may lead to excessive daytime sleepiness with hypersecretion of soporific cytokines.
Sleep restriction also reduces the levels of the appetite-regulating hormone, leptin, and therefore increases appetite. A recent controlled study in Spain showed that neuropeptide Y and leptin levels are increased in patients with obstructive sleep apnea (Am J Respir Crit Care Med 2005;171:183).
Diet, exercise, and more sleep?
Finally, should adequate sleep be a recommendation of weight loss programs, along with more exercise and proper diet? According to the authors, only a small increase in sleep may be needed; in their study, an extra 20 minutes of sleep per night was associated with a lower BMI. The authors also caution that their results do not establish a cause-and-effect relationship between restricted sleep and obesity.
