Sleep Deprivation May Contribute to Obesity »
The number of adults sleeping less than 7 hours per night has increased from 16-37% over the past 40 years. Currently 65% of all Americans are overweight or obese and this number is climbing. Is there a correlation between sleep deprivation and obesity? New research seems to suggest so!
As a sports medicine physician, about to finish my fellowship in a few months, I know first-hand the result of sleep deprivation. When I was swimming at the varsity level at Brown University, I weighed in at a trim 145 pounds with a body fat percentage of 4 percent. I am 5ft 10. Fast forward 10 years filled with sleep deprivation in medical school, residency and fellowship and despite leading a physically active life, my weight peaked at 185 pounds six months ago! That’s a gain of 40 pounds and a body mass index (BMI) of 26.5, clinically overweight. Thankfully with a more conscious effort on healthy living including plenty of sleep, I have been able to maintain a more healthy 170 pounds and 10% body fat over the last 6 months with a BMI of 24.4, within the normal range. Much of my weight gain is a direct result of sleep deprivation and stress, and my genetic predisposition to obesity- thanks mom and dad! The point I want to impress upon you is that 8 hours of regular sleep per night may be the easiest way you can lose weight and fight obesity!
There is much evidence to support this theory. The most recent study, published 5/18/09 in the Journal of Clinical Investigation looked at a specific calcium channel in cells of mice that has been found to regulate body weight maintenance and sleep. They found that mice lacking the CaV3.1 T-type calcium channel were more resistant to weight gain when fed a high fat diet. They were also able to feed normal mice a drug that blocks these channels and as a result the mice slept more and were resistant to weight gain. Lastly, obese mice were fed this drug and they reduced their body weight and fat percentage. They concluded that the gene better aligns feeding patterns and circadian rhythms which govern sleep and that drugs targeting this specific calcium channel may one day become an obesity fighting drug in humans.
There are other studies at the University of Chicago, Stanford University, and University of Wisconsin that found that sleep increases the hormone Ghrelin and decreases another hormone Leptin. Ghrelin is an appetite stimulating hormone released by the stomach. Leptin is a satiety and “fullness” hormone released by fat cells. They are essentially the Yin- Yang of appetite balance. The University of Chicago study also found that sleep deprivation caused subjects to crave high carbohydrate foods like sugary cakes and candy. Stanford and Wisconsin studied 1,024 people ages 30 to 60 for many years and confirmed that Ghrelin and Leptin changes with sleep deprivation and also noted a correlation of sleep deprivation with higher BMI.
Researchers at Columbia University looked at government data of 6115 people and found that people who sleep two to four hours a night are 73% more likely to be obese than those who get seven to nine hours. Those who get five or more hours of sleep a night are 50% more likely to be obese than normal sleepers. Those who sleep six hours are 23% more likely to be obese. The researchers reported, those who get 10 or more hours are 11% less likely to be obese.
What’s the take home point? Not only should you aim to sleep 8 hours per night, those 8 hours should also be at the same time of night. Sleeping irregularly and less than 8 hours puts you at risk for weight gain and obesity and all the complications that come with obesity. For this reason, avoid shift work if at all possible. If you think you are suffering from a lack of sleep, difficulty falling asleep or staying asleep, talk to your family physician or health care provider. Sleep well and shape up!
References:
1) Uebele, V. et al. Antagonism of T-type calcium channels inhibits high-fat diet–induced weight gain in mice. J. Clin. Invest. doi:10.1172/JCI36954. http://www.jci.org/articles/view/36954.
2) Sleep Loss May Equal Weight Gain. http://www.usatoday.com/news/health/2004-12-06-sleep-weight-gain_x.htm
3) Spiegel, K, Tasali, E, Penev, P, Van Cauter, E. Brief communication: Sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite. Ann Intern Med 2004; 141:846.
4) National Sleep Foundation. Sleep in America Poll, National Sleep Foundation, Washington, DC, 2002.
5) BMI calculator: http://www.nhlbisupport.com/bmi/
