Extending weekend sleep after weeknight sleep restriction improves insulin sensitivity

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SAN FRANCISCO–Men who habitually do not get enough sleep during the workweek may be able to improve their insulin sensitivity and thus lower their diabetes risk by getting adequate sleep, a new study finds. The results were presented Tuesday at The Endocrine Society’s 95th Annual Meeting in San Francisco.

The study showed that insulin sensitivity, the body’s ability to clear glucose (blood sugar) from the bloodstream, significantly improved after three nights of “catch-up sleep” on the weekend in men with long-term, weekday sleep restriction, said principal investigator, Peter Liu, MD, PhD, of Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, Calif.

Resistance to the hormone insulin is a known risk factor for diabetes. Others’ research has demonstrated harmful effects of experimental sleep restriction on insulin sensitivity in healthy, normal sleepers. The new study, according to Liu, gives information about the population of interest: people with “lifestyle-driven” restricted sleep for part of the week.

“Many of us restrict our sleep during the working week for occupational reasons, but not having enough sleep is harmful for metabolic health,” Liu said.

The good news, Liu said, is that the harmful effects on insulin sensitivity are reversible with adequate sleep. “Our study shows that those who regularly do not get enough sleep can improve their metabolic risk [for type 2 diabetes] by extending their sleep,” he said.

Liu and researchers from the University of Sydney in Australia studied 19 nondiabetic men, with an average age of 28.6 years, who for six months or longer (average, 5.1 years) received inadequate sleep during the workweek. On average, the men received only 6.2 hours of sleep each worknight but regularly caught up on their sleep on the weekends, sleeping an extra 37.4 percent, or 2.3 hours, per night, the authors reported. Their reported sleep times were verified by actigraphy, in which each man wore a small device on his wrist that monitored sleep-wake cycles.

The men spent three nights in a sleep lab on each of two separate weekends. The researchers randomly assigned the men to two of three sleep conditions: (1) 10 hours of sleep, (2) six hours of sleep or (3) 10 hours in bed, in which noises during deep sleep aroused them into shallow sleep without waking them. The six hours of sleep tested persistent sleep restriction.

On the fourth morning, the men had blood drawn to measure their blood sugar and insulin levels, for calculation of insulin sensitivity. Each individual had the same food intake during the study visits, so that diet would not influence the results, Liu said.

When the men slept 10 hours a night on each of three nights of catch-up sleep, their insulin sensitivity was much better than when they had persistent sleep restriction, the scientists found. Their insulin resistance test score also improved (decreased) with sleep extension.

“Sleep extension could prevent development of insulin resistance and diabetes in these individuals,” Liu stated.

The study received funding from the National Institutes of Health’s National Center for Advancing Translational Sciences and from Australia’s National Health and Medical Research Council.

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Founded in 1916, The Endocrine Society is the world’s oldest, largest, and most active organization devoted to research on hormones and the clinical practice of endocrinology. Today, The Endocrine Society’s membership consists of over 16,000 scientists, physicians, educators, nurses, and students in more than 100 countries. Society members represent all basic, applied, and clinical interests in endocrinology. The Endocrine Society is based in Chevy Chase, Maryland. To learn more about the Society and the field of endocrinology, visit our site at www.endocrine.org. Follow us on Twitter at https://twitter.com/#!/EndoMedia.