New research out today suggests that changes in sleep routine can cause you to gain weight. Sleeping just one hour less a night will lead to you eating an extra 200 calories the next day - the equivalent of a bagel.
Penn State University recently conducted a study of 342 teenagers who said they slept for seven hours a night. The teenagers who took part in the study had an average age of 17 and wore actigraph bracelets, which measured their cycles of activity and rest over seven days to estimate how long they slept each night.
The participants answered a food frequency questionnaire to see how many calories and snacks, and how much protein, fat, and carbohydrates they regularly consumed in the previous year. Researchers then analysed the relationships between sleep duration, day-to-day sleep variations and food intake. The results were adjusted for age, sex, race, and body mass index.
When the amount of time teenagers slept varied by just an hour - either less or more - they ate, on average, an extra 201 calories per day. They also consumed about 6g more total fat - the same as a teaspoon of butter or a milk chocolate truffle - and 32g more carbohydrates the day after - the equivalent of 100g of spaghetti. Disrupted sleep was also linked with a 60 per cent higher chance of night-time snacking on school nights, and 100 per cent higher chance of night-time munching on weekends.
Researchers say one possible explanation for the effect of changes to sleep may be that getting less sleep may make a teenager more sedentary the next day and so they become a 'couch potato' who snack in front of the telly. Another possibility is that shifts in sleep patterns result in a hormonal imbalance, causing teenagers to eat more.
Study lead author Fan He, of Penn State University College of Medicine, said: 'According to the data from our study, it's not how long you sleep that matters. 'It's about day-to-day variations in how long you sleep. It may be more important to have a regular sleep pattern than to sleep longer one day and shorter on another.