The surprising effect sleep deprivation can have on the body in just six weeks

Getting just an hour and a half less sleep a night for a few weeks could cause weight gain, a study has suggested.

Most adults need between seven and nine hours of sleep a night to stay healthy, but one in five adults in the UK aren’t getting enough sleep, and about a quarter are living with obesity.

Sleep deprivation has long been linked to changes in appetite, causing overeating and weight gain as a result, but a new study has suggested this can happen surprisingly quickly.

A study by researchers at Columbia University found getting insufficient sleep, even for just six weeks, is enough to make someone put on weight.

Marie-Pierre St-Onge, professor of nutritional medicine in the university’s department of medicine, said: “Getting adequate sleep may help reduce the risk of weight gain and obesity-related conditions like heart disease and diabetes.”

For the study, published in the journal Annals of Internal Medicine, 95 adults who usually get the recommended seven to eight hours of sleep a night were instructed to delay their sleep by 90 minutes for six weeks. They then slept at their usual time for another six weeks.

Their 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.

Researchers found participants gained an average of 1lb over the six weeks with less sleep. They also spent about 20 more minutes sedentary than usual.

“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.

Faris Zuraikat, assistant professor of nutritional medicine in Columbia University’s department of medicine, said: “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.”

According to scientists, not getting enough sleep is associated with higher levels of the hormone ghrelin, which increases appetite. This, in addition to feeling more tired and so less likely to exercise, can contribute to weight gain.

Naveed Sattar, professor of metabolic medicine at the University of Glasgow, who was not involved in the study, said: “Sleep is a critical part of a healthy lifestyle. When we do not get enough sleep, the hormones that regulate appetite become disrupted, making us feel hungrier and increasing the likelihood of overeating. Tiredness can also reduce physical activity, meaning we burn fewer calories during the day. In addition, being awake for longer simply provides more opportunities to eat.”

Alex Miras, professor of medicine at Ulster University, also explained a lack of sleep can impact the pancreas – but so can getting too much sleep.

He told The Independent: “A lack of sleep increases the levels of inflammation and insulin resistance around the body. The pancreas has to then work harder to bring the blood sugars down by increasing the amount of insulin it produces. This can also cause either weight gain or worse metabolic health. On the other extreme, too much sleep is also associated with worse metabolism.”