We all know that a good night’s sleep is essential for good living – past studies have shown that those who get less than eight hours of sleep per night become forgetful and unfocused, have impaired coordination and motor skills, have diminished sex drives, and are three times more likely to catch a cold than those who sleep longer. There have also been studies that link sleep deprivation to obesity, and that have shown that those who don’t get enough sleep have higher levels of a hormone called ghrelin, which triggers hunger, and may cause cravings for high-carbohydrate, high-calorie foods.
Following up on this research are two more recent studies, which seem to firmly establish sleep deprivation as a factor in obesity, and a hindrance to those interested in losing weight. In the first study, researchers at the Mayo Clinic presented findings indicating that people who were sleep-deprived ate 500 or more calories per day more than people who got enough sleep. In their study, 17 healthy but sedentary subjects agreed to spend 11 days and nights in a lab environment, in which all of their movements and everything they ate could be monitored by researchers.
At the three-day mark of the study, half of the group was awakened every morning after only 2/3 of their usual sleep time, while the other half of the group slept normally. The group that had been deprived of sleep tended to eat more the next day, an average of 549 calories more than in their usual diet. Lead study author Virend Somers says of the findings, “The magnitude of the effect – the fact that cutting down on sleep by a couple of hours a night over the course of a week or so can make you eat an average of 550 more calories a day – that’s the valuable message from this study. That’s a lot of extra calories.”
A newer study finds the same thing, but differently in men and women
The second study, published in the journal SLEEP, followed 27 subjects (both men and women) of normal weight, and between the ages of 30-45. In the first phase of the study, the subjects were first deprived of sleep (getting only four hours of sleep per night), and in the second phase they were allowed to get nine hours of sleep. These researchers found similar increases in caloric intake when the subjects were sleep-deprived, and no increases when the subjects got enough sleep.
Because this study closely monitored blood samples among the subjects, however, the researchers were able to determine that although both men and women increased their caloric intake after not getting enough sleep, the reasons for that seem to be different. Similar to findings in previous studies, sleep deprivation seemed to increase production of the hormone ghrelin (which stimulates hunger), but in men, not in women. In the women, another mechanism was causing the increase in calorie intake, a decrease in the hormone GLP-1 (which affects satiety, the sense of being “full” or satisfied after eating).
So for men, lack of sleep increased their caloric intake by giving them a bigger appetite and making them feel hungry. Whereas for women, sleep deprivation caused a similar increase in calories by making them feel less full, and unsatisfied by eating. As study author Marie-Pierre St-Onge, a researcher at the New York Obesity Nutrition Research Center, said about the findings, “Our results point to the complexity of the relationship between sleep duration and energy balance regulation. The state of energy balance, whether someone is in a period of weight loss or weight gain, may be critical in the metabolic and hormonal responses to sleep restriction.”
If you want to lose weight or maintain your weight, get enough sleep
Although the SLEEP study demonstrates that the effect of lack of sleep on people is complex, and is different for men and women, the end result seems to be the same as in previous studies: Lose sleep, gain weight. This information should be enough to remind everyone concerned about their weight to limit their “dieting” to cutting down on what they eat, not cutting down on how long they sleep. The latter may be sabotaging the former.