Is sleeping too much making you fat - or just the opposite?

New evidence came out last month linking lack of sleep with an increased risk of obesity. Research in the American Journal of Human Biology and the American Academy of Nutrition and Dietetics Journal, show that not getting enough shut-eye could affect glucose metabolism and even raise blood pressure. It may also affect how our appetites are regulated by causing increased energy consumption.

This new research draws upon the results of past sleep studies, showing a link between sleeping fewer than six hours a night and having an higher body mass index (BMI), or being obese. The link also seems to be stronger among children and teens.

Sleep may also impact appetite regulation by effecting part of the brain called the hypothalamus which produces the appetite hormones ghrelin and leptin. Leptin is especially important because it gives us the signal to stop eating because we are satiated. Too little sleep increases the secretion of ghrelin, making us hungrier and increase the amount of food we consume.

We are much more sedentary today than our society was in the past, meaning our physical activity levels have plummeted, while our caloric intake has remained relatively constant. Our ancestors slept an average of 9 hours in 1900. This average dropped to less than 7 hours over the past 10 years. Those who are physically active appear to get more sleep - perhaps they are more "physically" tired. This supports the old adage, use it or lose it. Our bodies seem to unconsciously demand to be exercised. Lack of exercise coupled with poor sleep, this spells trouble when trying to control weight.

The take home message here is the importance of getting enough sleep. Children and adult bodies need to be physically active to feed into a normal sleep and awake cycles. One of the most important aspects to weight control may be getting into the routine of climbing into bed at the same time each night to ensure ample rest. If you have trouble falling asleep, I am sure that my students can recommend several of their textbooks that are a sure thing to help you nod off at night. But there are also some foods that might help do the job. Try a little carbohydrates as a bedtime snack because they promote serotonin production that can make you drowsy. I guess there is something to that cookie and milk bedtime snack after all.

Dr. SeAnne Safaii, Ph.D., RD, is an assistant professor at the University of Idaho.