Lots of screening tests the link between sleep deprivation and obesity focused on severe sleep deprivation, such as participants limiting their sleep to about four hours a night. These studies suggest that this may lead to increased appetite and overeating, which in turn may contribute to weight gain.
However, because very few people can endure such severe sleep restrictions for more than a few days, the practical utility of this research is narrow and has not necessarily clarified whether more common and milder types of sleep deprivation, such as sleeping five to six hours a night, actually lead to weight gain.
This is the background for recent study by a research team from the Vagelos School of Medicine at Columbia University, who revealed that chronic, subtle sleep deprivation – which is estimated to affect about 30 percent of adults – can lead to weight gain.
“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,” he added. explained Marie-Pierre St-Onge, a professor at Columbia University specializing in nutritional medicine, in a release.
Less sleep, more weight
St-Onge and her research team studied 95 adults who typically slept at least seven hours a day and were at cardiovascular and metabolic risk. Participants were asked to postpone their bedtime by 90 minutes for six weeks, and their sleep time and physical activity were recorded using wrist-worn monitors.
For the next six weeks, participants maintained their usual sleep schedules. During both periods, researchers measured participants’ weight, waist circumference, body composition and fasting blood levels of several hormones involved in appetite regulation.
The analysis showed that during the period in which bedtime was delayed and sleep time was reduced by approximately 80 minutes, participants’ average weight increased by approximately 0.45 kilograms compared to the period in which they slept normally. Extrapolating these results over the course of a year, significant weight gain may be linked to chronic sleep deprivation.
Additionally, during the sleep-restricted period, the average amount of time spent sitting increased by 17 minutes per day. For postmenopausal men and women, sitting time increases by almost 30 minutes a day. In other words, even taking into account the longer time spent awake, participants spent more time sitting than when they were sleeping enough.
On the other hand, levels of the appetite-suppressing hormone leptin were actually higher during the sleep restriction period. The theory advanced in studies of severe sleep restriction that hormonal disruption leads to overeating does not hold, at least when it comes to leptin.
Next step
A previous study using a subset of the same participants (38 women) also found broader health implications. When women at high risk of cardiovascular and metabolic diseases had their sleep reduced by approximately 80 minutes a night over a six-week period, their insulin resistance, a risk factor for type 2 diabetes, increased. This effect was particularly pronounced in postmenopausal women.
What’s more, another study using the same participants found that subtle reductions in sleep time in men and women at high risk of heart disease made immune cells in the blood more likely to migrate to sites of inflammation.
This study suggests that even subtle sleep deprivation – which many people experience on a daily basis – can have a measurable impact on weight, sedentary behavior and appetite-related hormones. The discovery that the accumulation of even minor sleep deprivation can pose a health risk is a challenge to newfangled lifestyles that prioritize other activities over sleep.
“Together, our findings suggest that insufficient sleep increases the risk of obesity-related diseases such as type 2 diabetes and heart disease” – St-Onge says. “The next step is to understand what health benefits chronically sleep-deprived people can gain by improving sleep duration.” How much can reassessing your daily sleep amount support you manage your weight and prevent lifestyle-related diseases? Further research is needed to understand the mechanisms involved.
This story originally appeared on WIRED Japan and was translated from Japanese.