Update on the Relationship between Sleep and Metabolism

The Relationship between Sleep and Metabolism

Karine Spiegel, PhD, and colleagues published an article in the December 7, 2004 issue of the Annuals of Internal Medicine that suggests that sleep restriction can lead to weight gain. They found that sleep restriction (4 hrs /night) leads to decreased levels of the hormone Leptin and increased levels of Ghrelin, another hormone. The alteration of the levels of these appetite and energy regulating hormones was associated with increased hunger and appetite in the study. This study adds to the evidence linking insufficient sleep to obesity.

More recently, Dr. Henry Klar Yaggi and colleagues reported on a 15-year study that examined the association between sleep duration and the risk of developing type 2 diabetes mellitus. The prospective observational Massachusetts Male Aging Study found that men reporting short sleep duration (6 or less hours per night) and men reporting long sleep duration (more than 8 hours per night) were at significantly increased risk for developing diabetes compared to those getting 7-8 hours of sleep.

Insufficient nocturnal sleep can be caused by either a sleep disorder or voluntary sleep deprivation. Excessive sleep is usually caused by an underlying sleep disorder. Abnormal nocturnal sleep durations have been linked with obesity, impaired glucose tolerance, and diabetes mellitus.

It is important for physicians to counsel their overweight and obese patients to allow for 8 hours of sleep per night. Since obstructive sleep apnea is both a cause and consequence of obesity, practitioners should screen their obese patients for this common disorder. Useful symptoms to ask about include snoring, prolonged sleep duration, frequent nocturnal awakenings, and excessive daytime sleepiness.