Reciprocal association between rest-activity rhythm and depression in young adults: An ecological momentary...

Depressive symptoms commonly increase during young adulthood and have been associated with disruptions in rest-activity rhythms (RAR), but prospective within-person associations between daily RAR characteristics and depressive symptoms remain unclear. This study examined reciprocal within-person associations between daily RAR parameters and depression among young adults. A total of 319 participants (mean age = 19.16 years; 78.1% female) contributed 3155 analytic person-days during a 14-day wrist-actigraphy and ecological momentary assessment protocol. RAR parameters included acrophase, circadian quotient, intradaily variability, interdaily stability, and relative amplitude. Daily depression mean and daily depression instability were derived from repeated assessments. Bayesian dynamic structural equation models adjusting for prior-day perceived stress and 24-h light exposure, as well as sex, age, and season were used to estimate the cross-lagged associations between depression and RAR. Late acrophase on day t - 1 predicted high depression mean on day t (posterior median = 0.051, 95% credible interval [CrI] [0.002, 0.100]). Great depression instability on day t - 1 predicted low interdaily stability on day t (posterior median = -0.039, 95% CrI [-0.069, -0.008]). No other cross-lagged associations were supported. Exploratory analysis did not provide credible evidence of sex differences. These findings advance our understanding of daily interplay between depression and behavioral rhythmicity and shed light on chrono-interventions for mood problems among young adults.