Late bedtimes and less sleep can add extra pounds in healthy adults

A new study has claimed that healthy adults with late bedtimes and chronic sleep restriction are more susceptible to weight gain due to the increased consumption of calories during the late hours.

In the largest, most diverse healthy sample studied to date under controlled laboratory conditions, results show that sleep-restricted subjects who spent only four hours in bed from 4 am to 8 am for five consecutive nights gained more weight than control subjects who were in bed for 10 hours each night from 10 pm to 8 am.

The study 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.

Furthermore, the proportion of calories consumed from fat was higher during late-night hours than at other times of 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 in Philadelphia, said.

The study is published in the journal Sleep.