Getting a little less sleep each night can have a bigger impact on your health than you think. Researchers at Columbia University Vagelos College of Physicians and Surgeons found that adults who reduced their nightly sleep by about 80 minutes over six weeks gained an average of one pound and spent more time inactive.
The findings add to growing evidence that consistently getting enough sleep can play an important role in preventing weight gain and reducing the risk of obesity-related diseases.
“Our study shows that getting enough sleep can help reduce the risk of weight gain and obesity-related conditions, such as heart disease and diabetes,” says Marie-Pierre St-Onge, professor of nutritional medicine in Columbia’s Department of Medicine and Institute of Human Nutrition and leader of the study. “People tend to gain weight throughout 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.”
Looking beyond extreme sleep deprivation
Much of the previous research linking lack of sleep to obesity has focused on severe sleep deprivation, which often limits people to only four hours of sleep. Those studies have shown that extreme sleep loss can increase appetite and overeating, factors that contribute to weight gain.
However, most people find it difficult to tolerate such severe sleep restriction for more than a few days.
“These studies only show us what happens under the most extreme conditions and don’t tell us whether people who are mildly sleep deprived, like many Americans who sleep 5 or 6 hours a night, will gain weight,” St-Onge says.
To better reflect real life, researchers examined the effects of mild, chronic sleep loss, a pattern experienced by about 30% of adults.
Six weeks of less sleep led to measurable changes
The study included 95 adults who typically slept 7 to 8 hours each night. Over a six-week study period, participants delayed their usual bedtime by 90 minutes. For another six-week period, they followed their normal sleep schedule.
Throughout both phases, participants wore wrist monitors that tracked sleep and physical activity. The researchers also measured body weight, waist circumference, body composition, and fasting levels of several hormones involved in appetite regulation.
“While the one-pound weight gain seen with a modest reduction in sleep is not overwhelming, it is important to remember that this occurs in just six weeks,” says Faris Zuraikat, assistant professor of nutritional medicine in Columbia’s Department of Medicine and Institute of Human Nutrition and first author of the study. “Our study was designed to mimic the 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 significant weight gain.”
Sleeping less also means sitting more
The researchers found that the participants became less active during the sleep restriction phase. On average, sedentary time increased by 17 minutes per day. Among men and postmenopausal women, inactivity increased by almost 30 minutes each day.
“Even when we took into account the fact that they were awake longer when sleep was shorter, participants spent more time inactive than when they got enough sleep,” says Zuraikat. “This is notable, since more sedentary people have an elevated risk of chronic diseases.”
Previous research suggests broader health effects
The same group of participants has also been examined in related studies. In previous research, women at higher cardiometabolic risk who reduced their sleep by about 80 minutes each night for six weeks developed greater insulin resistance, a major risk factor for type 2 diabetes. The effect was especially pronounced in postmenopausal women.
Another study found that men and women at high risk for heart disease developed an influx of inflammatory cells in the heart after experiencing mild sleep restriction.
“Although more research is needed to better understand how sleep restriction leads to weight gain, all of our findings suggest that insufficient sleep increases the risk of obesity-related conditions, such as type 2 diabetes and heart disease,” says St-Onge.
“We now need to understand the health effects of improving sleep in those who do not get enough sleep on a regular basis.”
The study, titled “Skimping on sleep and its impact on weight and body composition: A pooled analysis of randomized trials,” was published July 6 in Annals of internal medicine.
The authors are Faris Zuraikat, Samantha Scaccia, Justin Cochran, Bin Cheng, Keith Diaz, Seth Creasy (University of Colorado), Brooke Aggarwal, Sanja Jelic, and Marie-Pierre St-Onge.
The authors report no conflicts of interest.
The research was supported by the American Heart Association (16SFRN27950012) and the National Institutes of Health (R01 HL128226, UL1 TR001873, P30 DK026687, R01 HL173190, R01 HL155190, R01 HL153642, K01 HL145023, R01 HL169991, R01 HL106041, R35 HL155670, R01 AG071032, R56 DK136601, P30 DK048520 and R01 DK128154).