Keeping a close eye on their daily sleep routine just got a whole lot more important, particularly for weight watchers.
Many previous studies that examine the link between sleep deprivation and obesity focused on severe sleep deprivation, such as restricting participants’ sleep to about four hours. These studies suggest that extreme sleep deprivation can lead to increased appetite and overeating, which may contribute to weight gain. However, very few people can endure such severe sleep restrictions for more than a few days. Previous research has not necessarily clarified whether mild sleep deprivation – under more realistic conditions, such as five to six hours of sleep per day – actually leads to weight gain. New research points to a connection between even mild, but chronic sleep loss and weight gain.
A study by a research team at Columbia University’s Vagelos College of Physicians and Surgeons has revealed that even chronic, mild sleep deprivation – which is estimated to affect about 30% of adults – can lead to weight gain.
“This study shows that getting enough sleep can help reduce the risk of not only weight gain but also obesity-related diseases such as heart disease and diabetes,” explains Marie-Pierre Santonje, a professor at Columbia University specialising in nutritional medicine. “People tend to gain weight throughout adulthood, and obesity is a major risk factor for heart disease. However, focusing solely on diet and exercise to prevent weight gain is short-sighted and not easy to sustain.”
Increased Sedentary Time and Weight Gain
Santongju and her research team studied 95 adults who typically slept at least seven hours a day and had cardiovascular and metabolic risks. These participants were asked to delay their bedtime by 90 minutes for six weeks, and their sleep duration and physical activity were recorded using wrist-worn monitors.
For another six weeks, the participants returned to their normal sleep schedules. During both periods, the researchers measured the participants’ weight, waist circumference, body composition and fasting blood levels of several hormones involved in appetite regulation.
Analysis revealed that during the period when bedtime was delayed and sleep duration was reduced by approximately 80 minutes, participants’ average weight increased by about 0.45kg compared to the period when they slept normally. Faris Zuraikhat, the lead author of the paper and an assistant professor of nutritional medicine at Columbia University, points out that the fact this occurred in just six weeks should not be overlooked because if this were extrapolated to a chronic sleep pattern over a year, it could lead to even greater weight gain.
In addition, during the sleep-restricted period, the average amount of time spent sitting increased by 17 minutes per day. When limited to men and postmenopausal women, sedentary time increased by nearly 30 minutes per day. In other words, even accounting for the longer time spent awake, the time spent sitting was longer than when participants had sufficient sleep. It did not follow that “more time awake means more physical activity.”