Less Sleep Linked to Weight Gain in Healthy Adults
Not getting enough sleep makes you put on more weight, a new study suggests.
Researchers found that healthy adults with late bedtimes and chronic sleep restriction are more susceptible to weight gain due to the increased consumption of calories during late-night hours.
In a laboratory experiment, researchers found that sleep-restricted subjects who spent only four hours in bed from 4 a.m. to 8 a.m. for five consecutive nights gained more weight than control subjects who were in bed for 10 hours each night from 10 p.m. to 8 a.m.
Researchers found an overall increase in caloric intake during sleep restriction, which was due to an increase in the number of meals consumed during the late-night period of additional wakefulness. What's more, the findings revealed that the proportion of calories consumed from fat was higher during late-night hours than at other times of the day.
"Although previous epidemiological studies have suggested an association between short sleep duration and weight gain/obesity, we were surprised to observe significant weight gain during an in-laboratory study," lead author Andrea Spaeth, a doctoral candidate in the psychology department at the University of Pennsylvania said in a statement.
The study, which will appear in the July issue of the journal SLEEP, involved 225 healthy, non-obese individuals between the ages of 22 and 50 years. Participants were randomly selected to either the sleep restriction or control condition and spent up to 18 consecutive days in the laboratory.
Meals were served at scheduled times and food was always available in the laboratory kitchen for participants who wanted to eat at other times of day. Researchers said participants could move around but were not allowed to exercise. However, they were allowed to watch TV, read, play video games, or perform other sedentary activities.
Researchers found that males gained more weight than females during sleep restriction and African Americans gained more weight than Caucasians.
"Among sleep-restricted subjects, there were also significant gender and race differences in weight gain," said Spaeth.
"African Americans, who are at greater risk for obesity and more likely to be habitual short sleepers, may be more susceptible to weight gain in response to sleep restriction. Future studies should focus on identifying the behavioral and physiological mechanisms underlying this increased vulnerability," she concluded.