A cross-sectional study published in the Journal of Affective Disorders found that depression was more common among adolescents who fall asleep later and/or sleep less.
The ROOTS study recruited adolescents (N=688) at secondary schools in the United Kingdom between 2005 and 2007. Participants were evaluated for sleep features using a combined heart rate and movement sensor and a subset of participants underwent semi-structured interviews to assess demographics and psychosocial measures. Depressive symptoms were evaluated using the Mood and Feelings Questionnaire (MFQ) at the target ages of 14.5, 16, and 17.5 years.
At baseline, participants were aged mean 14.48 (SD, 0.275) years, 56.40% were girls, 92.44% were not a minority, and 56.40% were considered to be “Wealthy Achievers” according to the Acorn socioeconomic status scale.
The average sleep duration was 7 hours and 44 minutes with sleep onset occurring at 23:44. Girls on average slept 18 minutes longer than boys (P <.001).
Self-reported sleep duration was 1 hour and 24 minutes shorter and onset 1 hour and 4 minutes later than the device-measured outcomes, however, sleep duration (r, 0.248) and onset (r, 0.466) were correlated between self-report and device-measured data.
At all-time points, girls had higher MFQ scores than boys (mean difference [MD] range, 3.49-5.36; all P <.001).
In the longitudinal model, higher MFQ score at age 14.5 years associated with a greater decline in symptoms with time (intercept, 0.398; P <.001; slope, 0.029; P <.048). Stratified by gender, the baseline value was significant among both boys and girls (intercept, boys: 0.328; girls: 0.451; both P <.001) but the decline in MFQ scores over time did not differ on the basis of gender (slope, boys: 0.027; P =.155; girls: 0.030; P =.222).
Significant predictors for MFQ scores were sleep duration on weekdays for both boys (intercept, -0.028; P =.046) and girls (intercept, -0.048; P =.003), sleep onset on weekdays for both boys (intercept, 0.033; P =.022) and girls (intercept, 0.034; P =.016), sleep onset on weekends for boys (intercept, 0.027; P =.008), and the change in sleep onset during the week for girls (slope, -0.018; P =.002).
The findings of this study may not be generalizable, as this study population was overwhelmingly White and most were socially advantaged.
The study authors concluded, “Cross-sectional associations with both sleep duration and sleep onset time were found, where sleeping less and later were associated with more depressive symptoms. Sleep onset time was a more robust predictor of contemporaneous depressive symptoms than sleep duration, accentuating the particular importance of adolescents going to sleep in a timely manner. Our cross-sectional findings highlight the importance of good sleep hygiene in adolescents, but also the need for a detailed investigation into the possibility and implications of reverse causality (whereby mental health predicts sleep).”
Thorburn-Winsor EA, Neufeld SAS, Rowthorn H, et al. Device-measured sleep onset and duration in the development of depressive symptoms in adolescence. J Affect Disord. 2022;310:396-403. doi:10.1016/j.jad.2022.05.051