A new study published in the journal Sleep says that if a healthy people going late to bed, leading to insufficient sleep are at a higher risk of gaining weight that the early sleepers.
Adding to this, researchers from University of Pennsylvania said that eating late at night also contributes to putting on the extra kilos.
The authors claimed their study to be the largest so far that demonstrates a clear connection between late night sleep with sleep deprivation and weight gain. The study was done on healthy people under controlled laboratory conditions.
The investigators compared two groups in focus, one of which had participants sleeping from 4 a.m. to 8 a.m. and another control group slept from 10 p.m. to 8 a.m. for five nights running.
Andrea Speath (a doctoral candidate in the psychology department at the University of Pennsylvania,) and team found that people who slept less consumed more food resulting in a higher in-take of calories. Late night meals have a higher overall fat content than other meals.
Speath said “"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."
The experiment was conducted at the Sleep and Chronobiology Laboratory at the Hospital of the University of Pennsylvania. It involved 225 people aged between 22 and 50 years, all of them healthy and non-obese. They were randomly selected either into the sleep restriction group or control group, and stayed in the lab for up to 18 days.
Set meals were served to all the participants at the same time each day. They had a free 24- hour access to the stock kitchen. Moving around was allowed barring exercise.
The study also showed that when sleep-deprived for several consecutive days:
- Men put on more weight than women
- African-Americans piled on the pounds more rapidly than Caucasians
"Among sleep-restricted subjects, there were also significant gender and race differences in weight gain. 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 behavioural and physiological mechanisms underlying this increased vulnerability."
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