Losing an hour and a half of sleep each night for six weeks is enough to gain a pound in weight, a new study released Monday found.
That’s because sleep loss is tied to a more sedentary lifestyle, which makes it easier to gain weight, according to researchers at Columbia University Vagelos College of Physicians and Surgeons.
For the study, nearly 100 adults, who normally slept 7-8 hours, delayed bedtime by 90 minutes – and found their overall time sitting down during the day increased by an average of 17 minutes. For men and postmenopausal women — groups that are more likely to be overweight — that time increased to nearly 30 minutes.
“Even when we accounted for the fact that they were awake longer when sleep was shortened, participants spent more time being inactive than when they got adequate sleep,” Faris Zuraikat, an assistant professor at Columbia’s Department of Medicine and Institute for Human Nutrition, explained in a statement.
“This is notable, as people who are more sedentary have elevated risk for chronic diseases,” he said. Obesity is a known risk factor for heart disease, cancer and type 2 diabetes.
One pound may not sound like a lot over the course of six weeks. But the researchers said the impact can build up over time.
“While the one-pound weight gain observed with modest sleep curtailment is not overwhelming, it is important to remember this is occurring over just six weeks,” said Zuraikat.
“Our study was designed to mimic sleep patterns that most adults experience chronically. When extrapolated to a full year, we would expect that losing less than an hour and a half of sleep per night could result in clinically meaningful weight gain,” he added.
In addition to six weeks with shortened sleep, the study’s participants spent another six weeks getting the normal amount of sleep.
Their sleep and activity levels during both periods were tracked using a wrist monitor and researchers also measured body weight, waist circumference, body composition and levels of several hormones known to increase or suppress appetite.
The study builds on past research linking poor sleep to other negative health outcomes.
Previous studies of the same adults showed that women who shorted their sleep by 80 minutes for six weeks had increased insulin resistance, a risk factor for type 2 diabetes, and that men and women with an elevated risk to their heart health saw increased inflammatory cells in the heart after restricting sleep.
“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,” Marie-Pierre St-Onge, a professor of nutritional medicine who was part of the study, said.
“Now we need to understand the health effects of improving sleep in those who fail to get adequate sleep on a regular basis,” she noted.
Federal recommendations say healthy adults should get 7-9 hours of sleep a night. Still, about a third of American adults, the majority of whom are women, aren’t getting enough.
That leads to an increased risk of disease, accidents, a lack of focus and slowed reaction time.
Not getting enough sleep also stimulates the hungry hormone grehlin. That can lead to overeating unhealthy foods, according to UCLA Health.
A healthy diet and exercise can help people to sleep better. “Preliminary research suggests that certain foods including milk, fatty fish, tart cherry juice and kiwi fruit may improve sleep,” Harvard Health says.
