Losing about 80 minutes of sleep each night for six weeks led participants to gain an average of one pound.
People also became more sedentary during the period of reduced sleep, even after accounting for extra waking time.
Researchers say consistently getting enough sleep may be an important part of maintaining a healthy weight.
Most people know that getting enough sleep helps them feel more alert the next day. But new research suggests that regularly cutting sleep short — even by what may seem like a modest amount — could also affect body weight.
Researchers at Columbia University found that adults who reduced their nightly sleep by about 80 minutes for six weeks gained an average of one pound and spent more time being inactive than when they followed their normal sleep schedule. The findings add to growing evidence that sleep is an important part of overall health, alongside nutrition and physical activity.
“Our study shows that getting adequate sleep may help reduce the risk of weight gain and obesity-related conditions like heart disease and diabetes,” researcher Marie-Pierre St-Onge said in a news release.
“People tend to gain weight over the course of their adulthood, and obesity is a major risk factor for heart disease. But focusing on eating a healthier diet and getting more physical activity to offset weight gain is simplistic and can be difficult to maintain.”
How the study worked
The study pooled data from two randomized crossover trials involving 95 adults ages 20 and older who were already sleeping at least seven hours per night and had elevated cardiometabolic risk. Rather than bringing participants into a sleep laboratory, researchers conducted the study while people lived their normal daily lives.
Each participant completed two six-week phases. During one phase, they maintained their usual sleep schedule. During the other, they delayed their bedtime by 90 minutes each night, resulting in an average loss of about 80 minutes of sleep.
Throughout both phases, participants wore wrist monitors that tracked their sleep and physical activity. Researchers also measured changes in body weight, waist circumference, body composition, and fasting levels of several hormones involved in regulating appetite.
What the findings mean for consumers
By the end of the sleep-restriction phase, participants had gained about one pound on average and were spending roughly 17 more minutes per day being sedentary.
Among men and postmenopausal women, sedentary time increased by nearly 30 minutes per day. Researchers found that participants remained less active even after accounting for the fact that they were awake longer.
While a one-pound increase over six weeks may sound small, the researchers say it could become more meaningful if similar sleep habits continue over months or years.
They also point to earlier work involving some of the same participants, which found that mild, chronic sleep restriction was linked to increased insulin resistance in women with elevated cardiometabolic risk and greater inflammation associated with heart health.
For consumers, the findings suggest that sleep deserves a place alongside healthy eating and regular exercise when thinking about long-term weight management. Although the study doesn't prove that improving sleep alone will prevent weight gain, it indicates that consistently getting enough rest may play a meaningful role in supporting overall health.
“Though more research is needed to further understand how sleep restriction leads to weight gain, all of our findings suggest that insufficient sleep increases the risk of obesity-related conditions like type 2 diabetes and heart disease,” St-Onge said.
“Now we need to understand the health effects of improving sleep in those who fail to get adequate sleep on a regular basis.”