Not Sleeping Enough? You May Be at Risk for Obesity
Trying to lose weight? Maybe you should take a nap. That’s right, a little extra sleep—maybe hitting the snooze button a couple times—could be the key to taking off those extra pounds. Sounds crazy, doesn’t it?
According to recent studies, adults and children who were sleep deprived tended to be obese. At age three, inadequate sleep predicts obesity by age 7. As little as a half hour less sleep per night can result in significantly more obesity, particularly at younger ages. Studies in multiple populations and over the entire lifespan have demonstrated higher weights and increased eating associated with less sleep. Additionally, according to American Cancer Society data, those with sleep deficits also have higher mortality.
This is an unfortunate trend. Over the past 50 years, we in the United States have reduced our average total sleep time by about 2 hours per night. There are many reasons for this drop in sleep time, including job and school demands, late night TV, availability of 24/7 entertainment, and more. This change coincides with the obesity epidemic we are now seeing, as two-thirds of us are overweight or obese.
Usually, when we think of losing or controlling weight, we look for ways to be more active—walk, play tennis, and so on. How can spending more time in bed help us lose weight? This is not the same as resting. It does not justify being a couch potato. Regular exercise is important, but it is sleep that seems to keep our appetites under control.
Our bodies are not passive during sleep, and sleep affects many of our systems. Our sleep needs vary with age, children needing more than adults. Most adults require 8 hours, more or less. In later years, the same number of hours is needed, but the sleep cycle changes. Many older Americans stay asleep about 6 or 7 hours at night, but add a 1-2 hour mid-day nap. People who say they can function on fewer hours are probably wrong. If you tend to nod off when sitting at your desk, or worse, when driving, you are sleep deprived.
During sleep, our fat cells produce the hormone leptin which tells our brains we have sufficient fat stored and therefore do not need to eat any more. When we are sleep-deprived, leptin production is suppressed and the opposing hormone, ghrelin, is released by the gut, signaling hunger. Ghrelin does not just make us hungry; it makes us seek out high-fat foods. Sleep deprivation studies show an increase in ghrelin and a corresponding decrease in leptin levels. While not conclusively proven, the evidence suggests this as a possible explanation for the tendency for higher weights in people who sleep less. Unfortunately, giving people leptin does not seem to suppress appetites the way getting enough sleep does.
The need for enough sleep is being recognized by more than scientists. In Hong Kong, a territory wide health awareness and promotion program entitled “Better Health for a Better Hong Kong” has recognized the adverse effects of long working hours with reduced sleeping times on the health of the Hong Kong Chinese working population. Maybe it’s time for everyone to rethink their schedules. To achieve and maintain a normal weight we must eat correctly, exercise regularly, and get some more sleep!
1. Taheri S, et al. Short sleep duration is associated with reduced leptin, elevated ghrelin and increased body mass index. PLoS Medicine. 2004;1(3):210-217. Accessed at www.plosmedicine.org.
2. http://www.bristol.ac.uk/researchreview/2004/1113989409. Accessed 1 December 2007.
3. Littman AJ, et al. Sleep, ghrelin, leptin and changes in body weight during a 1-year moderate-intensity physical activity intervention. Internat. J. Obesity (2007) 31:466-475.
4. Ko GTC, et al. Association between sleeping hours, working hours and obesity in Hong Kong Chinese: the ‘better health for better Hong Kong’ health promotion campaign. Internat. J. Obesity (2007) 31:254-260.