How Does Sleep Affect Body Weight?

With some cities weighing in on the obesity epidemic by planning to ban big sugary drinks and Disney planning to ban junk food ads, one could get the impression that the battle with obesity is being won on the home front. However, our overeating seems to be a more basic problem.
The Harvard School of Public Health suggests that sleep is an obesity prevention source.




“Researchers speculate that there are several ways that chronic sleep deprivation might lead to weight gain, either by increasing how much food people eat or decreasing the energy that they burn.

“Sleep deprivation could increase energy intake by:

• Increasing hunger: Sleep deprivation may alter the hormones that control hunger. One small study, for example, found that young men who were deprived of sleep had higher levels of the appetite-stimulating hormone ghrelin and lower levels of the satiety-inducing hormone leptin, with a corresponding increase in hunger and appetite—especially for foods rich in fat and carbohydrates.

• Giving people more time to eat: People who sleep less each night may eat more than people who get a full night’s sleep simply because they have more waking time available. Recently, a small laboratory study found that people who were deprived of sleep and surrounded by tasty snacks tended to snack more—especially during the extra hours they were awake at night—than when they had adequate sleep.

• Prompting people to choose less healthy diets: Observational studies have not seen a consistent link between sleep and food choices. But one study of Japanese workers did find that workers who slept fewer than six hours a night were more likely to eat out, have irregular meal patterns, and snack than those who slept more than six hours.


“Sleep deprivation could decrease energy expenditure by:

• Decreasing physical activity: People who don’t get enough sleep are more tired during the day, and as a result may curb their physical activity. Some studies have found that sleep-deprived people tend to spend more time watching TV, less time playing organized sports, and less time being physically active than people who get enough sleep. But these differences in physical activity or TV viewing are not large enough to explain the association between sleep and weight.

• Lowering body temperature: In laboratory experiments, people who are sleep-deprived tend to see a drop in their body temperatures. This drop, in turn, may lead to decreased energy expenditure. Yet a recent study did not find any link between sleep duration and total energy expenditure.


The Bottom Line: Sleep is a Promising Target for Obesity Prevention
“There is convincing evidence that getting a less than ideal amount of sleep is an independent and strong risk factor for obesity, in infants and children as well as in adults. Most of the research thus far, however, has consisted of observational studies, and it remains to be seen whether teaching children or adults how to get a better night’s sleep can lower their risk of obesity or help them lose weight. Randomized clinical trials that are currently underway may soon provide more answers.

“Some researchers have cautioned against being too quick to promote sleep as an answer to the obesity epidemic, given the shortcomings of the research conducted to date. Yet from a public health perspective, there is little risk in encouraging healthy sleep through lifestyle changes, such as setting a consistent bedtime, limiting caffeine late in the day, and curtailing high-tech distractions in the bedroom. Good sleep habits have other benefits, too, like boosting alertness at school or work, improving mood, and enhancing overall quality of life. That’s all the more reason to put a long night’s sleep on the short list for obesity prevention,” The Harvard publication concluded.

The good news in this is that maybe we don’t have to venture further into the nanny state to prevent obesity as the New York ban suggests. Getting a little more sack time may be all we need.