Nighttime exposure to outdoor artificial light was associated with poorer sleep patterns, mood disorders, and anxiety in adolescents, according to findings published in JAMA Psychiatry. In a large cohort study of adolescents in the United States, artificial light at night (ALAN) was linked to later weeknight bedtime, fewer minutes of sleep, and greater prevalence of past year mood and anxiety disorders.
Diana Paksarian, PhD, of the Genetic Epidemiology Research Branch, Intramural Research Program, National Institute of Mental Health, Bethesda, Maryland, and colleagues used data from the National Comorbidity Survey-Adolescent Supplement, a nationally representative cross-sectional survey of adolescents living in the US. Individuals aged 13-18 years were invited to complete the survey between February 2001 and January 2004.
Trained interviewers collected demographic and clinical data during in-person interviews. Habitual sleep patterns were assessed by self-report, including weeknight bedtime, weeknight sleep duration, weekend bedtime delay, and weekend oversleep. Past year mood, anxiety, behavior, and substance use disorders were captured with structured diagnostic interviews.
Outdoor ALAN was derived from satellite imagery data, averaged across census blocks. ALAN values were expressed as units of radiance and stratified into quartile based on intensity. Logistic regression was used to assess the impact of ALAN exposure on sleep patterns and psychiatric symptoms, adjusted for individual- and area-level covariates.
The study cohort comprised 10,123 adolescents (mean age, 15.2 years; 51.3% boys; 65.6% non-Hispanic white). ALAN was positively associated with markers of social disadvantage, including racial/ethnic minority status, lower family income, lower parental education, and having 1 or more first relatives born outside the United States.
Median ALAN among non-Hispanic white adolescents was lower than that experienced by adolescents of all other ethnicities (P <.001). Adolescents with a family income-to-poverty ratio ≤1.5 had a lower median ALAN compared to adolescents with a ratio >6 (P =.005).
In adjusted regression models, higher ALAN was associated with later weeknight bedtime and greater weekend sleep duration. Compared with the lowest quartile of ALAN, adolescents in the highest quartile went to bed 29 (95% CI, 15-43) minutes later and had 11 (95% CI, 2-19) fewer minutes of sleep. Additionally, each median absolute deviation increase in ALAN was associated with 1.07 (95% CI, 1.00-1.14) times the odds of mood disorder and 1.10 (95% CI, 1.05-1.16) times the odds of anxiety disorder.
In unadjusted models, ALAN was associated with major depressive disorder, dysthymia, bipolar disorder, agoraphobia, social phobia, and specific phobias. In fully adjusted models, only the associations with bipolar disorder (OR, 1.19; 95% CI, 1.05-1.35) and specific phobias (OR, 1.18; 95% CI, 1.11-1.26) persisted.
This study provides evidence for the negative impact of ALAN on adolescent sleep patterns and mental health. While the use of ALAN as a proxy for individual-level light exposure is a significant limitation, results are consistent with prior research on light-at-night exposure and sleep disturbances.
“Future studies should elucidate whether public interventions designed to reduce the brightness or spectral composition of outdoor nighttime lighting could benefit mental and sleep health among youth, especially those who face other sources of social disadvantage,” investigators wrote.
Paksarian D, Rudolph KE, Stapp EK, et al. Association of outdoor artificial light at night with mental disorders and sleep patterns among US adolescents [published online July 8, 2020]. JAMA Psychiatry. doi:10.1001/jamapsychiatry.2020.1935