Sleep and weight

In a survey by the Robert Koch Institute, about a third of adults reported sleep problems that may be relevant. Women were affected twice as often. The data are over ten years old.^[5]

An analysis of 11 studies with 172 people found that after shortened sleep, participants ate 385 kcal more a day on average. Expenditure did not change measurably.^[2]

There was also a trial the other way round. 80 adults with overweight who usually slept under 6.5 hours got advice on sleeping longer. They slept about 1.2 hours more and ate 270 kcal a day less than the control group.^[3]

In a small study of 10 people on reduced energy intake, participants were hungrier with 5.5 hours of sleep time than with 8.5 hours. They also lost less fat and more other body mass.^[4]

Most studies are small or short. They show an effect on food intake, but not what this means for one person over years.

The German Sleep Society advises:^[6]

• get up at the same time every day
• go to bed only when you feel sleepy
• move regularly
• avoid dozing off during the day and in the evening
• don't use alcohol to fall asleep, and avoid unusually heavy meals in the evening

On their own, though, such rules do little for real sleep disorders. In 42 studies they did worse than cognitive behavioural programmes and exercise.^[7] For lasting insomnia, the European guideline names these programmes as the first choice, including in digital form.^[8]

According to EFSA, even 100 mg of caffeine close to bedtime can disturb sleep in some adults.^[9] A review of 24 studies found 45 minutes less sleep on average and advises having the last coffee at least 8.8 hours before bed.^[10] The amount matters more than the clock: in a trial of 23 young men, 100 mg made no difference 4 hours before, while 400 mg still disturbed sleep 12 hours before.^[11]

So find out what suits you. More under Caffeine.

Night shifts go along with higher odds of overweight, with a ratio of 1.23 in 28 observational studies.^[12] Whether this can be changed is open. The German Sleep Society mentions short naps before a night shift and no caffeine in the 4 hours before sleep.^[13]

Weight and breathing pauses are linked. In a study of 690 adults, 10% more weight went with about 32% more pauses, and 10% less with 26% fewer.^[14] According to the society, losing weight can reduce sleep apnoea but usually does not remove it.^[15] Loud snoring with pauses or strong daytime sleepiness should be checked by a doctor. Don't stop using a breathing device on your own.

Sleep is no trick for losing weight. But it is part of how easy your everyday life feels. If you are always tired even though you spend enough time in bed, talk to your doctor.