Researchers from the University of Pennsylvania say that people who regularly go to bed late are more likely to gain weight because of the late-night eating they indulge in.
Researchers from the University of Pennsylvania have found that "Early to bed, early to rise" doesn't only make people "healthy, wealthy and wise" but also keeps them from putting on extra weight.
In the study on the largest sample of healthy adults under controlled laboratory conditions till date, the researchers found that people who regularly went to bed late at night gained more weight than people who slept early. Authors of the study say the reason for the weight gain is that people who go to bed late at night are more likely to consume high-calorie food items as late-night snacks.
"A number of epidemiological studies have found an association between short sleep duration and weight gain, and ultimately obesity," said senior study author Namni Goel, PhD, research associate professor of Psychology in Psychiatry, Division of Sleep and Chronobiology at Penn, in a press release. "We wanted to examine this in a controlled experimental study to determine whether we would observe weight gain over a short period of time when subjects were sleep-restricted. We also sought to determine the source of such weight gain--that is, whether it was due to an additional intake of calories beyond what was needed to maintain body weight."
The study was conducted on 225 healthy, non-obese individuals, aged between 22 and 50 years. Participants were randomly divided into two groups. The participants of the first group were subjected to sleep restrictions while the second group was subjected to controlled sleeping conditions. All participants spent 18 consecutive days in the laboratory. The first group slept for only four hours a night, from 4 AM to 8 AM. The second group slept for 10 hours, from 10 PM to 8 AM. All participants were served meals at scheduled times. However, food was always available to anyone who wanted to eat at times apart from meal times. Participants were allowed to walk around but couldn't exercise. For recreational purposes, they were allowed to watch TV, play video games, read and perform other sedentary activities.
Researchers found that participants who received four hours of sleep for five consecutive days gained more weight than participants who received 10 hours of sleep daily. They also observed that sleep restricted participants consumed more calories because of extra meals they consumed owing to the additional hours they were awake. Most of the calories these participants consumed in the day were during their late night meals. Authors also found that males tended to put on more weight than females and African Americans gained more weight than Caucasians.
Weight gain has been listed as a risk factor for obstructive sleep apnea (OSA), reports the American Academy of Sleep Medicine in a press release. This disorder is said to have a great adverse effect on a person's health as well as quality of life. The severity of this disorder is directly proportionate to the weight of a person. There is an extremely high prevalence of OSA in people with morbid obesity
The results of the study are published in the July issue of the journal SLEEP.
