Aug. 12, 2009 - If you're getting too little sleep, you may also be getting diabetes.

People at risk of diabetes tend to get too little sleep. They also tend to exercise too little and eat unhealthy Western diets. Is poor sleep really a diabetes risk factor?

Yes, suggests a study by University of Chicago researchers led by Plamen Penev, MD, PhD.

"If confirmed by future larger studies, these results would indicate that a healthy lifestyle should include not only healthy eating habits and adequate amounts of physical activity, but also obtaining a sufficient amount of sleep," Penev says in a news release.

Five men and six women volunteered for the study. Their average age was about 40. They were a little overweight and didn't exercise much, but were otherwise healthy. They tended to sleep just under eight hours a day.

During two 14-day periods, they stayed in a lab where their sleep, activity, diet, and blood chemistry were carefully monitored. They weren't allowed to exercise, and junk food was always at hand.

For one of the 14-day periods, they were allowed to sleep for 8.5 hours a day. During the other period, they were allowed no more than 5.5 hours sleep each day. Sleep researchers say it's rare for a person to need less than six hours of sleep daily.

As their sleep times shortened, the volunteers went to bed later (at half past midnight rather than at 11:15 p.m.) and got up earlier (at 6 a.m. rather than 7:45 a.m.).

With all the junk food lying around and with so little physical activity, they gained more than 4 pounds of weight regardless of how much they slept.

What was different was their ability to control their blood sugar. When sleeping too little, the volunteers' blood sugar was higher on a glucose-tolerance test. They also became less sensitive to the blood sugar-lowering hormone insulin.

"When the unhealthy aspects of the Westernized lifestyle are combined with reduced sleep duration, this might contribute to the increased risk of many overweight and sedentary individuals developing diabetes," Penev says.

The study appears in the Journal of Clinical Endocrinology & Metabolism.