Sleep is Good for the Waistline

You are likely to have heard Americans are getting fatter. Eating fast and processed foods and a sedentary lifestyle are likely contributors. Today, almost 70% of Americans are overweight and this is a public health disaster. Officials in New York City sounded the alarm and intervened by banning trans fats but that is hardly enough. It is recognized that there are many other causes. By definition, you are considered obese if your body mass index is over 30.

Another prevalent health issue in the US is problems with sleeping. Almost 20 million people have sleep apnea and about one third of Americans are not getting enough sleep. There is also a high association between sleep disorders and being overweight. But did you know that almost 80% of overweight adults report sleep problems? A study followed women for 16 years and found that those sleeping less than 5 hours a night had a 30% greater chance of gaining 30 lbs or more over that time. How is that for a correlation!

Sleep deprivation has many effects including increasing irritability, memory issues, reduced immune function, risk of heart disease, diabetes and obesity. The connection between obesity and sleep has been reported many times. Predictably, sleepy people are apt to not exercise regularly. Reduced activity with even consistent caloric intake can pile on the pounds. On top of this, our bodies own metabolism works against us.

Hormonal changes are induced during sleep deprivation. The so called hunger hormones, leptin and ghrelin are appetite stimulating hormones whose levels are altered in sleep-deprived individuals. So when you are tired, the signals are interpreted as being hungry and you eat! It turns out that hunger and sleep induced fatigue alters the physiology of humans similarly.

Our brains also make a chemical called endocannabinoid 2-arachidonoylglycerol or 2-AG. You might have guessed it is chemically related to the active chemical in marijuana and has some of the same effects. It is likely that the cause of the hunger arising from limited sleep is similar to the munchies from smoking pot. 2-AG is associated with pleasure and appetite and is elevated in those that are sleep deprived stimulating the brain's reward system. Researchers found that restricting sleep from eight and one half to four and one half hours, led to the consumption of an extra 1000 calories in the form of "fatty rewarding snacks" during the evening. These results provide obvious implications for weight gain from sleep deprivation.

Hunger correlates with 2-AG levels observed in the blood. Sleep deprived individuals had levels of 2-AG that were one third higher than those with a full night's sleep. For those sleeping normally, 2-AG builds during the day peaking in the early afternoon, while those with limited sleep maintained high levels of 2-AG well into the evening. Therefore 2-AG maybe a new target for therapy to prevent weight gain.

There is also hope in taking advantage of this connection between weight and sleep behavior. If you can achieve more normal sleep, this may help you with weight loss and vice versa.

Medical Discovery News is hosted by professors Norbert Herzog at Quinnipiac University, and David Niesel of the University of Texas Medical Branch. Learn more at