Sleep Enough

Sleep Enough

From stress reduction to improving long-term memory, the effects of a good night’s sleep was well known. Now, latest research indicates that it also helps you shed weight
If sleeping to lose weight sounds like a dream, wake up.

Weight & Watch

The power of sleep in regulating appetite, body weight and risk of Type 2 diabetes in adults and children is so strong that some scientists wonder if it may soon be the newest weapon in the battle against obesity. “Can a good night’s sleep make us slimmer?” asks Danish nutrition researcher Arne Astrup in an editorial in this month’s International Journal of Obesity. Maybe, Astrup concludes, citing a growing body of research that points to sleep as a key player in hunger and appetite control.

Kids need 13 hours

The latest evidence comes from a study of 422 Canadian children, ages 5 to 10. Researchers at Quebec’s Laval University found that youngsters who slept 8 to 10 hours per night, had 3.5 times more risk of being overweight than a similar group of children who slept 12 to 13 hours nightly.

Even when other factors—parental obesity, participation in sports, family income and hours spent watching television, using a computer or playing video games—were factored into the equation, the study found that sleep proved to be the best predictor of body weight, especially for boys, according to Angelo Tremblay, a professor of physiology and nutrition at Laval and the study’s lead author.

Add this report to a number of others, including a long-term study of some 7,000 children published last year by British researchers. They found that the length of time children slept as preschoolers could alone predict their weight at age 7. As the team noted in the British Medical Journal, children who slept less than 11 hours at night at age 2 1/2 were significantly more likely to be obese at age 7 than those who slept 12 hours or more.

It works for adults too

Sleep seems to count for adults, too. A German study of 8,000 men and women found that sleeping difficulties were linked with an increased risk of obesity and with developing Type 2 diabetes—the kind that is related to body weight. Harvard University’s Nurses’ Health Study has also shown that participants who slept less than five hours per day had an increased risk of developing Type 2 diabetes over a 10-year period, compared to those who slept more.

How does it work?

How might sleep impact body weight and development of diabetes?

That’s still not known, but there are some promising leads. Among the leading suspects: leptin, ghrelin and cortisol—hormones altered by lack of sleep and known to regulate appetite. Just how much skipping sleep may affect body weight is illustrated by a small study of lean young men in a sleep lab at the University of Chicago.

During the 16-day study, missing a couple of hours of sleep per night wreaked havoc with leptin and cortisol levels, which fueled the participants’ hunger.

“Their bodies were screaming ‘famine’ despite the fact that they didn’t need to eat,” noted Eve Van Cauter, lead author of the study. “They responded as if they were missing about 1,000 calories a day.”

Skipping sleep also pushed these otherwise-healthy young men into impaired glucose tolerance, a step toward diabetes. During the study, their insulin and blood sugar levels suddenly resembled those of adults 65 to 80 years old. The good news: Hunger, hormones and blood sugar returned to normal with sleep.

Average sleep time down

In the past 20 years, the average amount of nightly sleep for adults has declined about one-and-a-half hours per night. Compare that to the national rise of body weight “and they are an exact mirror image,” noted Van Cauter — just a hint that chronic sleep loss may play a role in the obesity epidemic. How much of a role is uncertain. Lack of sleep can also be a sign of stress, which also fuels appetite. As Astrup writes, “it may prove difficult to disentangle the causes of impaired sleep from its effects.” Besides, there could be something simpler at work: “When we sleep more,” Astrup notes, “we simply have less time in which to eat.”