Non-food Things
Reduced deep sleep may raise type 2 diabetes risk
By Sue Mueller
Jan 1, 2008 - 9:08:52 AM

TUESDAY Jan 1, 2008 (foodconsumer.org) -- Suppression of slow-wave sleep or deep sleep decreases an individual’s ability to regulate blood sugar metabolism and increase the odds of developing type 2 diabetes, according to a study published in the "Early Edition" of the Proceedings of the National Academy of Science, available online Dec. 31, 2007.

The study led by researchers at the University of Chicago Medical Center found three nights of selective slow-wave sleep suppression reduced insulin sensitivity in young and healthy people.

The tested individuals experienced reduced sensitivity to insulin, but no higher insulin level was produced to compensate for the loss, resulting in reduced glucose tolerance and increased odds of becoming diabetic.

The researchers said the decrease in insulin sensitivity was comparable to that caused by gaining 20 to 30 pounds of body weight.

Studies have showed reduced sleep quantity impairs glucose metabolism and appetite regulation leading to higher risk of obesity and diabetes. But this study demonstrated that reduced sleep quality could have the same effect.

"These findings demonstrate a clear role for slow-wave sleep in maintaining normal glucose control," said Esra Tasali, MD, lead author of the study and assistant professor of medicine at the University of Chicago Medical Center.   "A profound decrease in slow-wave sleep had an immediate and significant adverse effect on insulin sensitivity and glucose tolerance."

The subjects enlisted for the study were nine lean, healthy men and women age 20 to 31.   During the first two nights, subjects sleep without disturbance.   During the next three nights, they were subject to sounds administered through speakers beside the bed. They were monitored for their brain waves every night.

The sounds used were at a level that disrupts deep sleep, but does not cause a full awakening.   The researchers were able to decrease slow-wave sleep by about 90 percent.

"This decrease in slow-wave sleep resembles the changes in sleep patterns caused by 40 years of aging," Tasali said. Young adults spend 80 to 100 minutes per night in slow-wave sleep, while people over age 60 generally have less than 20 minutes. "In this experiment," Tasali said, "we gave people in their 20s the sleep of those in their 60s."

At the end of three nights of slow-wave sleep suppression, the study subjects received intravenous glucose and the researchers tested the levels of glucose and insulin every few minutes.

As a result, the subjects experienced a 25 percent reduction in sensitivity to glucose and a 23 percent increase in blood glucose levels.   Eight out of nine participants did not experience an increase in secretion of insulin to compensate for the lost sensitivity to insulin.

"Previous studies from our lab have demonstrated many connections between chronic, partial, sleep deprivation, changes in appetite, metabolic abnormalities, obesity, and diabetes risk," said said Eve Van Cauter, PhD, professor of medicine at the University of Chicago and senior author of the study.