Diabetes Risk Increases
with Lack of Deep Sleep

Failing to sleep deeply for just three nights in a row has the same negative effect on the body's ability to manage insulin as gaining 20 to 30 pounds, diabetes researchers report in Proceedings of the National Academy of Sciences.

In fact, young adults who do not get enough deep sleep may be increasing their risk of type 2 diabetes.

According to the study, three nights of interrupted sleep effectively gave people in their 20s the glucose and insulin metabolism of people three times their age.

Previous studies have demonstrated that not getting enough hours of sleep affects the body's ability to manage blood sugar levels and appetite, increasing the risk of obesity and diabetes.

Glucose Control Needs "Slow-Wave" Sleep
This current study provides the first evidence linking poor sleep quality — specifically the loss of deep or slow-wave sleep — to increased diabetes risk, says the University of Chicago Medical Center research team.

"These findings demonstrate a clear role for slow-wave sleep in maintaining normal glucose control," says lead author Dr. Esra Tasali. "A profound decrease in slow-wave sleep had an immediate and significant adverse effect on insulin sensitivity and glucose tolerance."

The researchers suggest that improving the quality of sleep, especially for people as they age or if they are obese, could be an important step in preventing the onset of type 2 diabetes.

The researchers recruited five men and four women, all lean and healthy, who were between the ages of 20 and 31. The researchers first observed the participants for two nights of uninterrupted sleep, during which they slept for 8.5 hours, to establish their normal sleep patterns.

Then they observed the same participants over a three-night study period, during which the researchers deliberately disturbed their sleep when their brain waves indicated the beginning of slow wave sleep.

The sounds used to interrupt the sleep patterns were loud enough to move the participants to a different level of sleep but not loud enough to fully wake them.

According to the researchers, the participants could recall hearing between three and 15 noises at night, although they were interrupted on average 250 to 300 times. The interruptions increased in number each night, as the participants' need for deep sleep increased.

"This decrease in slow-wave sleep resembles the changes in sleep patterns caused by 40 years of aging," says Dr. Tasali.

Young adults spend 80 minutes to 100 minutes per night in slow-wave sleep, while people over age 60 generally have less than 20 minutes.

"In this experiment," she says, "we gave people in their 20s the sleep of those in their 60s."

Aging and Sleep Quality a Factor
At the end of each study, the researchers gave intravenous glucose (a sugar solution) to each participant, and then took blood samples every few minutes to measure the levels of glucose and insulin, the hormone that controls glucose uptake.

When the researchers analyzed the data they learned that the participants were almost 25 percent less sensitive to insulin after nights of interrupted sleep.

As their insulin sensitivity declined, they needed to make more insulin to process the same amount of glucose, or blood sugar.

However, in all but one subject, their bodies did not make more insulin. As a result, they had 23 percent more blood-glucose, the equivalent of glucose levels in an older adult with impaired glucose tolerance.

The researchers also found that the participants who typically had the least amount of slow-wave sleep during the nights they were not interrupted experienced the greatest decline in insulin sensitivity during the study.

The alarming rise in the prevalence of type 2 diabetes is generally attributed to the epidemic of obesity combined with the aging of the population.

"Previous studies from our lab have demonstrated many connections between chronic, partial, sleep deprivation, changes in appetite, metabolic abnormalities, obesity, and diabetes risk," says study author Eve Van Cauter, Ph.D.

"These results solidify those links and add a new wrinkle, the role of poor sleep quality, which is also associated with aging," she says.

"These findings shed light on a problem faced by many elderly, that of fragmented sleep and less time spent in restorative sleep," said Dr. Andrew Monjan, chief of the Neurobiology of Aging Branch at the National Institute on Aging.

"More research is needed into the link between insufficient sleep and common metabolic disturbances of later life, such as type 2 diabetes and obesity," concludes Dr. Monjan.

Always consult your physician for more information.

Online Resources

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American Academy of Sleep Medicine

American Diabetes Association

National Diabetes Education Program

National Diabetes Information Clearinghouse

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

National Institute on Aging

National Sleep Foundation

Proceedings of the National Academy of Sciences - Slow-wave sleep and the risk of type 2 diabetes in humans