Getting a little less sleep each night can have a greater impact on your health than you realize. Researchers at Columbia University’s Vagelos College of Physicians and Surgeons found that adults who reduced their nightly sleep by about 80 minutes for six weeks gained an average of about half a kilogram and spent more time engaged in sedentary activities. The findings reinforce the growing evidence that getting enough sleep can play an important role in preventing weight gain and reducing the risk of obesity-related diseases. The study, titled “Skimping on Sleep and Its Impact on Body Weight and Composition: A Pooled Analysis of Randomized Trials,” was published in the Annals of Internal Medicine.

Looking Beyond Extreme Sleep Deprivation

“Our study shows that getting enough sleep can help reduce the risk of weight gain and obesity-related diseases such as heart disease and diabetes,” said Marie-Pierre St-Onge, professor of nutritional medicine at Columbia University’s Institute of Medicine and Institute of Human Nutrition, and lead author of the study. “People tend to gain weight as they age, and obesity is a major risk factor for heart disease. However, focusing exclusively on a healthier diet and more physical activity to counteract weight gain is too simplistic and is often difficult to sustain.”

Much of the previous research linking poor sleep to obesity has focused on severe sleep deprivation, in which participants were often limited to just four hours of sleep. These studies have shown that extreme sleep deprivation can increase appetite and lead to overeating—factors that contribute to weight gain. However, such a severe restriction of sleep is tolerable for most people for only a few days.

“These studies only show us what happens under the most extreme conditions and do not tell us whether people with mild sleep deprivation—such as many Americans who sleep 5 or 6 hours a night—gain weight,” says St-Onge. To better reflect reality, the researchers examined the effects of chronic, mild sleep deprivation—a pattern that occurs in about 30% of adults.

Six Weeks of Reduced Sleep Led to Measurable Changes

The study included 95 adults who normally slept between 7 and 8 hours each night. During a six-week study period, the participants pushed back their usual bedtime by 90 minutes. During a subsequent six-week period, they returned to their normal sleep schedule. Throughout both phases, participants wore wristbands that tracked sleep and physical activity. The researchers also measured body weight, waist circumference, body composition, and fasting levels of various hormones involved in appetite regulation.

“While the one-pound weight gain observed with moderate sleep deprivation isn’t overwhelming, it’s important to remember that this happens within just six weeks,” said Faris Zuraikat, assistant professor of nutritional medicine in the Department of Medicine and at the Institute for Human Nutrition at Columbia University, and lead author of the study. “Our study was designed to mimic the sleep patterns that most adults chronically experience. Extrapolated over an entire year, we would expect that a sleep loss of less than one and a half hours per night could lead to clinically significant weight gain.”

Less Sleep also led to More Inactivity

In addition to weight gain, the researchers observed another important change: Participants were significantly less active during the period of restricted sleep. On average, they spent 17 more minutes sitting each day than during the phase with adequate sleep. This effect was particularly pronounced among men and postmenopausal women, whose daily inactivity increased by nearly 30 minutes.

It is noteworthy that this increase in inactivity could not be explained solely by the fact that the participants were awake longer due to shorter sleep. Even after accounting for the additional time spent awake, they spent a larger portion of their day engaged in sedentary or physically undemanding activities. The researchers therefore suspect that sleep deprivation not only affects sleep duration but also reduces motivation and energy for physical activity.

These findings are particularly relevant to health, as physical inactivity is considered an independent risk factor for numerous chronic diseases. People who are less active in their daily lives and spend more time sitting have an increased risk of obesity, cardiovascular disease, type 2 diabetes, and other metabolic disorders. The study thus shows that even a moderate reduction in sleep duration—if sustained over several weeks—can not only contribute to weight gain but also negatively influence physical activity levels, thereby further increasing the risk of long-term health consequences.

Earlier Studies Point to More Far-Reaching Health Effects

The participants in this study were also followed in several complementary studies that provide additional evidence of the health consequences of chronic, moderate sleep deprivation. The results show that the effects of insufficient sleep extend far beyond potential weight gain and can influence various metabolic and cardiovascular processes.

For example, women with pre-existing elevated cardiometabolic risk developed significantly greater insulin resistance following a six-week reduction in sleep duration of an average of 80 minutes per night. In this condition, the body’s cells become less sensitive to the hormone insulin, causing blood sugar levels to rise and increasing the risk of developing type 2 diabetes. This effect was particularly pronounced in postmenopausal women, a population group that already has an increased risk of metabolic diseases due to hormonal changes.

Another study with the same group of participants also showed evidence of inflammatory changes in the cardiovascular system. Following the period of restricted sleep, an increased number of inflammatory cells were detected in the heart tissue of men and women at elevated risk for heart disease. Chronic inflammatory processes are considered a key mechanism in the development and progression of cardiovascular diseases, as they can, among other things, promote the formation of vascular deposits and impair the function of the cardiovascular system.

Taken together, these findings illustrate that even a moderate reduction in sleep duration—if sustained over several weeks—can have measurable effects on key metabolic and inflammatory processes in the body. According to study lead author Marie-Pierre St-Onge, the findings to date suggest that insufficient sleep increases the risk of obesity-related diseases such as type 2 diabetes, cardiovascular disease, and other chronic conditions. At the same time, she emphasizes that further research is needed to better understand the biological mechanisms and to investigate whether improving sleep duration can reduce these health risks.

Measures to Improve Sleep Quality

The present study results underscore the importance of good sleep quality as a modifiable health factor. To promote restful sleep, scientific guidelines specifically recommend maintaining a regular sleep-wake cycle, in which both bedtime and wake-up times are kept as consistent as possible. In addition, the sleep environment should be optimized in terms of light, noise, and room temperature, as these environmental factors significantly influence sleep continuity. It is also recommended to reduce the consumption of caffeine, nicotine, and alcohol in the hours before bedtime, as these substances can disrupt sleep architecture and impair sleep quality.

Regular physical activity has also been shown to improve sleep, although intense physical exertion immediately before bedtime should be avoided. In addition, it is recommended to limit the use of electronic devices in the evening, as the short-wavelength (blue) light emitted by screens can inhibit melatonin secretion and thereby delay the circadian sleep-wake rhythm. Overall, numerous studies show that even relatively simple behavioral measures can sustainably improve sleep quality and thus make an important contribution to the prevention of obesity, metabolic disorders, and cardiovascular diseases.