It’s common knowledge that not getting enough sleep is bad for your health. There are clear correlations between sleep deprivation and cardiovascular problems and metabolic conditions. Now, a new study published in Annals of Internal Medicine finds that even a small amount of sleep deprivation can be consequential: When about 100 people intentionally shorted themselves on sleep for six weeks, their appetite hormones shifted, they burned less energy despite being awake longer, and they gained weight.
The findings reinforce the fact that even something that seems as harmless as sleeping for six hours a night instead of seven—roughly what the participants in this study did—has negative effects on the body.
There have been a number of studies on experimental sleep restriction. In previous experiments conducted in sleep labs, researchers have limited people to just four or five hours a night over a number of days. In fact, an earlier study led by one of the researchers behind the latest study required people to sleep less than four hours a night for five days. When they checked at the end, they found that people in the study ate about 300 calories more than they had at the start.
This time, the goal was “a more realistic evaluation of what would happen if we asked people to restrict their sleep by 1.5 hours, to a level that's similar to what we generally observe in the population,” says Marie-Pierre St-Onge, director of the Center of Excellence for Sleep and Circadian Research at Columbia University.
The optimum amount of sleep varies by individual, but most people need between seven and nine hours a night. In this study, the researchers instructed 95 people, who normally slept around 7.5 hours a night, to go to bed 1.5 hours later than usual for six weeks, while getting up at the same time. They wore wrist monitors and had their blood hormone levels tested, among other measures, to assess any changes happening over the course of the
