When people who weren’t getting enough sleep took measures to sleep for longer, they ate fewer calories per day and lost weight without changes to their diet or exercise
Sleeping for about an hour longer each night seems to help people lose weight – if they aren’t getting enough shut-eye to begin with, at least.
A single session of advice on better sleep habits helped people reduce their energy intake by 270 calories a day compared with a control group, without any efforts to change what they ate or to exercise more.
The results are promising, but larger and longer trials are need to confirm if the approach helps people lose weight in the long term, and if it helps those who are already getting enough sleep, says Rebecca McManamon, a spokesperson for the British Dietetic Association.
Previous studies have shown that restricting people’s sleep makes them eat more food and put on weight, probably because it disrupts appetite control mechanisms, but it wasn’t known if sleeping for longer would have the opposite effect.
Esra Tasali at the University of Chicago and her colleagues tested out the idea by recruiting 80 people who normally got no more than 6.5 hours of sleep a night, which is a little less than the recommended 7 to 8 hours. They had an average body mass index of 28, which is classed as being moderately overweight.
Half the group were randomly picked to get advice on how to sleep longer, aiming for 8.5 hours a night. This included tips on keeping to consistent bedtimes and avoiding using phones, computers and watching TV in the last hour before sleep.
For the next two weeks, participants wore activity trackers that recorded when they were asleep and drank chemically labelled water. Then, they provided four urine samples to the researchers, from which their calorie intake was determined. They also weighed themselves every morning and had a body composition scan at the end of the trial.
People in the control group had no change in their sleep patterns and put on a little weight over the two weeks. But those who received the advice slept 1.2 hours a night longer, on average. Their associated drop in calories meant they lost nearly half a kilogram. People reported that cutting out screen use in the evening had the biggest impact on getting more sleep, says Tasali.
Journal reference: JAMA Internal Medicine, DOI: 10.1001/jamainternmed.2021.8098
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