Artificial outdoor light at night may disrupt adolescents’ sleep and raise the risk for psychiatric disorders, a new study suggests.
Researchers tracked the intensity of outdoor light in representative urban and rural areas across the country using satellite data from the National Oceanic and Atmospheric Administration. They interviewed more than 10,123 adolescents living in these neighborhoods about their sleep patterns, and assessed mental disorders using well-validated structured scales. They also interviewed the parents of more than 6,000 of the teenagers about their children.
The study, in JAMA Psychiatry, found that the more intense the lighting in your neighborhood, the more sleep was disrupted and the greater the risk for depression and anxiety. After adjustment for other factors such as sex, race, parental education and population density, they found that compared with the teenagers in the one-quarter of neighborhoods with the lowest levels of outdoor light, those in the highest went to bed, on average, 29 minutes later and reported 11 fewer minutes of sleep.
Adolescents living in the most intensely lit neighborhoods had a 19 percent increased risk for bipolar illness, and a 7 percent increased risk for depression. The study is observational, and does not prove cause and effect.
The senior author, Kathleen R. Merikangas, a senior investigator with the National Institute of Mental Health, said that future policy changes could make a difference. In the meantime, she said, “At least as individuals, we ought to try to minimize exposure to light at night.”