Outdoor Light Linked with Teens’ Sleep, Mental Health
Research shows that adolescents who live in areas that have high levels of artificial light at night tend to get less sleep and are more likely to have a mood disorder relative to teens who live in areas with low levels of night-time light. The research was funded by NIMH and was published in JAMA Psychiatry.
“These findings illustrate the importance of joint consideration of both broader environmental-level and individual-level exposures in mental health and sleep research,” says study author Dr. Diana Paksarian, a postdoctoral research fellow at NIMH.
Daily rhythms, including the circadian rhythms that drive our sleep-wake cycles, are thought to be important factors that contribute to physical and mental health. The presence of artificial light at night can disrupt these rhythms, altering the light-dark cycle that influences hormonal, cellular and other biological processes. Researchers have investigated associations among indoor artificial light, daily rhythms and mental health, but the impact of outdoor artificial light has received relatively little attention, especially in teens.
In this study, Paksarian, Dr. Kathleen Merikangas, senior investigator and chief of NIMH’s Genetic Epidemiology Research Branch and co-authors examined data from a nationally representative sample of adolescents in the United States.
To gauge the teens’ exposure to outdoor artificial light at night, the researchers used satellite imagery data to calculate the average artificial light levels for each census block group in the U.S. As expected, levels of artificial light at night varied according to certain neighborhood-level factors, such as urbanicity, socioeconomic levels and population density.
Importantly, teens who lived in areas with high levels of artificial light at night tended to report later weeknight bedtimes and shorter weeknight sleep duration. The analyses showed that, on average, teens in areas with the highest levels of outdoor light went to bed about 29 minutes later and got 11 fewer minutes of sleep than did teens in areas with the lowest levels.
“Although environmental light exposure is only one factor in a more complex network of influences on sleep and behavior, it is likely to be an important target for prevention and interventions in adolescent health,” says Merikangas.