WASHINGTON (dpa-AFX) - According to a new study published in the Annals of Internal Medicine, regularly missing about 90 minutes of sleep each night can lead to nearly 1 pound of weight gain in six weeks. If this pattern continues, it could add up to almost 9 pounds in a year.
The study combined data from two clinical trials involving 95 adults aged 20 and older. All participants were considered at higher risk of heart and metabolic diseases, but usually slept at least seven hours a night before the study.
Each participant completed two six-week study periods. During one phase, they continued their normal sleep routine and got at least seven hours of sleep each night. During the other phase, they went to bed 90 minutes later than usual, reducing their nightly sleep by about 78 minutes on average.
Researchers tracked participants' sleep using wrist-worn devices and sleep diaries to ensure they adhered to the schedule. Before and after each study period, the team measured participants' weight, waist size, and body composition using MRI scans. Blood samples were also taken to measure hormones linked to hunger and energy balance, including leptin and ghrelin.
The study found that participants gained an average of 0.45 kg, or nearly 1 pound, after six weeks of getting less sleep compared with when they slept normally. Their waist size also increased by about half a centimeter, suggesting that some of the extra weight was around the abdomen, which is linked to a higher risk of heart disease. MRI scans showed an increase in overall body size, but no major change in body fat or muscle.
'Our study shows that getting adequate sleep may help reduce the risk of weight gain and obesity-related conditions like heart disease and diabetes,' said lead author Marie-Pierre St-Onge, a professor of nutritional medicine in Columbia's Department of Medicine and Institute for Human Nutrition. '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.'
The researchers also found that levels of leptin, a hormone linked to the body's energy stores, increased during the sleep restriction period. However, there was no change in GLP-1, a hormone that helps control appetite. People who slept less also spent about 17 extra minutes each day sitting or being inactive. However, the amount of moderate or vigorous exercise they did remained the same.
Among participants whose daily calorie burn was measured, there was no major difference between the normal sleep and reduced sleep periods. This suggests the weight gain was more likely caused by eating more and spending more time inactive rather than burning fewer calories.
Overall, the study showed that even a small loss of sleep over several weeks can lead to noticeable weight gain and more sedentary behavior. Researchers recommended that getting enough sleep should be considered an important part of maintaining a healthy weight and lowering the risk of obesity, heart disease, and metabolic disorders.
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