Study reveals getting less sleep could cause you to gain weight

By Stephen Beech

Skimping on sleep leads to people putting on weight, reveals new research.

Scientists found that participants in the study who reduced shut-eye by around 80 minutes a night for six weeks gained an average of 1 pound (0.45 kilograms).

They also spent more time sitting, according to the findings of the American study published in the journal Annals of Internal Medicine.

Research leader Marie-Pierre St-Onge said: "Our study shows that getting adequate sleep may help reduce the risk of weight gain and obesity-related conditions like heart disease and diabetes.

"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."

She explained that much of what's known about the link between insufficient sleep and obesity is based on small, brief studies of people who endured severe sleep restriction.

Such studies show that severe sleep deprivation leads to changes in appetite and overeating, which can contribute to weight gain over time.

But most people can't tolerate severe sleep deprivation for more than a few days.

St-Onge said: "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 five or six hours of sleep a night, will gain weight."

To investigate the effects of chronic mild sleep deprivation, a sleep pattern adopted by around 30% of adults, St-Onge and her team at Columbia University Vagelos College of Physicians and Surgeons in New York City recruited 95 adults who usually get seven to eight hours of sleep per night.

Participants were instructed to delay their normal bedtime by 90 minutes for one six-week phase and to get the usual amount of sleep for another six-week phase.

Sleep and activity levels were measured throughout each phase with a wrist monitor, along with changes in body weight, waist circumference, body composition, and fasting levels of several hormones known to increase or suppress appetite.

Study first author Faris Zuraikat said: "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.

"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."

Sedentary time also increased by an average of 17 minutes per day during the sleep-restriction phase overall, and by nearly 30 minutes per day for men and postmenopausal women.

Zuraikat said: "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.

"This is notable, as people who are more sedentary have elevated risk for chronic diseases."

In a previous study of a subset of the same participants, St-Onge's team found that women with increased cardiometabolic risk who shortened their sleep by around 80 minutes a night over six weeks had increased insulin resistance, a risk factor for type 2 diabetes.

The effects were more pronounced in postmenopausal women.

In another study of the same group, the researchers found that men and women with elevated heart risk had an influx of inflammatory cells in the heart after mild sleep restriction.

St-Onge said: "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."

She added: "Now we need to understand the health effects of improving sleep in those who fail to get adequate sleep on a regular basis."