Let There Be…Darkness
You know sleep is important for your health, but did you know it’s important for your waistline, too? A recent study sheds light on the impact sleep has on your metabolism. Phyllis C. Zee, MD, PhD, Northwestern Medicine neurologist, and Northwestern University Feinberg School of Medicine professor and chief of sleep medicine in neurology, was the principal investigator on the study.
Study Shows the Impact of Disrupted Sleep
Scientists placed 20 healthy adults aged 18 to 40 into two different groups for two nights. Both groups were allowed the recommended eight hours of sleep. However, one group was in complete darkness both nights, while the other was in darkness on the first night and exposed to 100 lux, not particularly bright but enough brightness to light a stairway, on the second night. The scientists measured the participants’ melatonin, brain waves, blood oxygen levels, heart rate and breathing. Oral glucose tolerance tests were also conducted the following morning.
Not only did participants sleep better in total darkness, they also had much lower levels of insulin. This is a major finding, because insulin is the hormonal signal to the body to help regulate glucose levels. Higher levels of insulin are associated with insulin resistance, a condition that can lead to diabetes. These types of changes in metabolism are associated with weight gain and obesity. The study reveals that light exposure during sleep or at night may ultimately increase the risk for weight gain, regardless of how much you eat or exercise.
The Trick to Losing Weight: Sleep in Darkness
“Our preliminary findings show that a single night of light exposure during sleep acutely impacts measures of insulin resistance,” says Ivy Cheung Mason, PhD, who was a postdoctoral fellow at Feinberg School of Medicine during the time of study. “Light exposure overnight during sleep has been shown to disrupt sleep, but these data indicate that it may also have the potential to influence metabolism.”
“In addition to exercise and nutrition, these results indicate that manipulating light may be a novel way to improve sleep and metabolic health,” says Dr. Zee. It might be time to curb the late-night Netflix bingeing. The study linked the impact of light exposure at night, such as from phones or TV screens, to your metabolism. So if you’re looking to lose weight, don’t drift off to sleep watching late-night TV; turn off the tube and catch your Z’s in a dark room instead.