We don’t have to stay awake for hours to see the effects of insufficient sleep on our health. Even a short deficit of around 80 minutes can, when repeated systematically, affect our weight and physical activity.

Study of researchers from Columbia University Vagelos College of Physicians and Surgeons revealed that adults who slept about 80 minutes less each night for six weeks gained an average of nearly half a pound while also spending more time sitting.

Prevention of weight gain therefore does not depend only on diet and exercise. Adequate sleep seems to be an equally important factor.

Fewer minutes? Weight gain

Previous studies on the link between sleep and obesity looked at extreme sleep deprivation conditions, limiting participants to four hours of sleep. We know that such a severe shortage can increase appetite and encourage overeating. However, it does not necessarily reflect the everyday life of most people.

This time, the researchers wanted to study more realistic data, such as chronic, milder sleep deprivation, which occurs when we consistently put off bedtime to finish a task, watch another episode, or spend some time on our cell phones.

The study involved 95 adults who typically slept seven to eight hours a night. For one period of six weeks they went to bed 90 minutes later than usual, while in a second period of the same duration they followed their normal schedule.

During the study they wore wrist devices that recorded their sleep and activity. The scientists also monitored weight, waist circumference, body composition and certain hormones related to appetite regulation.

How the weight changed in six weeks

When they slept less, the participants gained an average of about 450 grams. The change may not seem significant, but it happened in just six weeks.

The researchers point out that such a pattern, if continued over many months, could lead to more substantial weight gain. This is, however, an estimate and not a result measured over a year. So the findings don’t mean that every person who misses 80 minutes of sleep will necessarily gain weight.

The study mainly highlights the importance of consistency, as a seemingly small sleep deficit may not be negligible after all when it becomes a habit.

Less sleep, more inactivity

The change was not limited to the scale. During the period of reduced sleep, sedentary time increased by an average of 17 minutes per day. In postmenopausal men and women the increase was closer to 30 minutes.

In fact, the participants did not sit more simply because they stayed awake longer. Even when the researchers accounted for extra waking time, physical activity remained reduced.

The fatigue that follows insufficient sleep can make us less willing to exercise, walk or even carry out small, everyday movements. When this happens again, our energy costs may be affected.

Sleep as part of prevention

Previous analyzes in the same group of participants reported that women at increased cardiometabolic risk who slept about 80 minutes less each night for six weeks showed greater insulin resistance, a major risk factor for type 2 diabetes, with the effect being more pronounced in postmenopausal women.

Although more research is needed to clarify the mechanisms linking sleep and weight, it is becoming clear that rest is not a luxury or a habit independent of diet and exercise.

Weight management and metabolic health care is not limited to fewer bites and more steps. Adequate, quality sleep is a daily need, which should not be underestimated.