Getting enough sleep is often seen as a luxury, but growing evidence suggests it is just as important as eating a healthy diet and staying active.
A new study from Columbia University Vagelos College of Physicians and Surgeons found that regularly sleeping about 80 minutes less each night may lead to gradual weight gain and a more inactive lifestyle.
The findings were published in the Annals of Internal Medicine.
Many adults sleep only five or six hours each night because of work, family responsibilities, or screen time.
While a single short night is unlikely to cause lasting harm, scientists have wondered what happens when people lose a small amount of sleep for weeks or months. Earlier studies mainly examined extreme sleep deprivation, where volunteers slept only about four hours per night.
Those experiments showed increased hunger and overeating, but they lasted only a few days because very little sleep is difficult to tolerate.
To better reflect real life, Professor Marie-Pierre St-Onge and colleagues recruited 95 healthy adults who normally slept seven to eight hours each night. During one six-week period, participants delayed bedtime by about 90 minutes.
During another six-week period, they followed their normal sleep schedule. Researchers monitored sleep and physical activity using wrist devices and measured body weight, waist size, body fat, and hormones linked to appetite.
On average, participants slept about 80 minutes less each night during the sleep-restriction phase.
By the end of six weeks, they had gained about one pound. Although one pound may seem small, researchers say the effect could become much larger if the pattern continues for months or years.
Participants also became more sedentary, spending about 17 extra minutes each day inactive. Among men and postmenopausal women, inactive time increased by almost 30 minutes daily.
The team believes several biological changes may explain the findings. Previous studies involving many of the same participants showed that reduced sleep increased insulin resistance, especially in postmenopausal women. Insulin resistance raises the risk of type 2 diabetes. Another related study found signs of increased inflammation affecting the heart after mild sleep restriction.
The results suggest that insufficient sleep may influence body weight not only by changing appetite but also by reducing daily movement. When people feel tired, they may naturally spend more time sitting or resting instead of being physically active.
The study has important strengths because it lasted six weeks and closely reflected the amount of sleep loss many adults experience. However, it cannot determine exactly how these changes would continue over many years, and the study included a relatively small number of participants.
Overall, the findings suggest that protecting sleep should be considered an important part of weight management and long-term health, alongside healthy eating and regular exercise.
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