How Losing Around 80 Minutes of Sleep a Night Could Drive Weight Gain and Inactivity

Key Takeaways: 

• Adults who cut their nightly sleep by about 80 minutes over six weeks gained roughly one pound (around 0.45 kg) on average and became more sedentary, Columbia University researchers found.
  
• Modest over six weeks, but the team estimates that sustaining this mild sleep loss for a year could cause clinically meaningful weight gain – a pattern affecting around 30% of adults.
  
• Related work in the same participants linked mild sleep restriction to greater insulin resistance and heart inflammation, pointing to a wider risk of type 2 diabetes and heart disease.
  
  
  

Why modest sleep loss deserves attention

Trimming a little sleep each night may carry more weight for your health than you might realise. Researchers at Columbia University Vagelos College of Physicians and Surgeons found that adults who shortened their nightly sleep by about 80 minutes over a six-week period gained an average of one pound and spent more of their waking hours being inactive.

The findings add to a growing body of evidence suggesting that consistently getting enough sleep may play an important role in preventing weight gain and in lowering the risk of obesity-related disease. Rather than pointing solely to diet and exercise, the results place sleep alongside them as a factor worth taking seriously.

“Our study shows that getting adequate sleep may help reduce the risk of weight gain and obesity-related conditions like heart disease and diabetes,” says Marie-Pierre St-Onge, a professor of nutritional medicine in Columbia’s Department of Medicine and Institute for Human Nutrition and the study leader. “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.”

Looking beyond extreme sleep deprivation

Much of the earlier research connecting poor sleep with obesity has centred on severe sleep deprivation, frequently restricting people to as little as four hours of sleep a night. Those studies indicated that extreme sleep loss can heighten appetite and encourage overeating – behaviours that in turn contribute to weight gain.

The difficulty is that such severe restriction is hard for most people to sustain for more than a few days, which limits how far the results can be applied to everyday life. Very few people live with four hours of sleep for weeks at a time, so the relevance of those findings to the wider population has remained uncertain.

“These studies only show us what happens under the most extreme conditions and don’t tell us if mildly sleep-deprived people, like a lot of Americans who get 5 or 6 hours of sleep a night, will gain weight,” St-Onge says.

To reflect real-world habits more closely, the researchers set out to examine the effects of chronic, mild sleep loss – a pattern estimated to affect around 30% of adults.

Six weeks of less sleep led to measurable changes

The study involved 95 adults who typically slept between seven and eight hours each night. During one six-week phase, participants delayed their usual bedtime by 90 minutes, which shortened their nightly sleep. During a separate six-week phase, they kept to their normal sleep schedule, allowing each participant to serve as their own comparison.

Across 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 regulating appetite, building a detailed picture of how the body responded to the change.

“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,” says Faris Zuraikat, assistant professor of nutritional medicine in Columbia’s Department of Medicine and Institute for Human Nutrition and first author of the study. “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.”

Less sleep also meant more sitting

Alongside the change in weight, the researchers found that participants became less active during the sleep-restriction phase. On average, sedentary time rose by 17 minutes per day. Among men and postmenopausal women, inactivity climbed by nearly 30 minutes each day.

Notably, this increase in sitting held up even after accounting for the extra waking hours that come with shorter sleep – so the added inactivity was not simply a matter of being awake for longer.

“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,” Zuraikat says. “This is notable, as people who are more sedentary have elevated risk for chronic diseases.”

Earlier research suggests broader health effects

The same group of participants has featured in several related studies, which together suggest that the consequences of mild sleep loss may extend well beyond weight. In one earlier investigation, women with increased cardiometabolic risk who reduced their sleep by about 80 minutes each night for six weeks developed greater insulin resistance – an important risk factor for type 2 diabetes. The effect was particularly pronounced in postmenopausal women.

A separate study found that men and women with an elevated risk of heart disease developed an influx of inflammatory cells in the heart after undergoing mild sleep restriction, hinting at a possible mechanism linking short sleep to cardiovascular harm.

“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 says.

“Now we need to understand the health effects of improving sleep in those who fail to get adequate sleep on a regular basis.”

About the study

The study, titled “Skimping on Sleep and Its Impact on Body Weight and Composition: A Pooled Analysis of Randomized Trials,” was published on 6 July 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.