BACKGROUND: While growing evidence implicates sleep-wake and circadian rhythm disturbances (SCRDs) in the onset and course of mood and psychotic disorders, longitudinal studies using objective measures are limited. This clinical cohort study examined whether actigraphy-derived SCRDs (sleep duration, timing, and efficiency) predicted transition to (i) any full-threshold mental disorders; and then specifically: (ii) full-threshold bipolar or psychotic disorders or (iii) other full-threshold (i.e. depressive or anxiety) disorders, in youth accessing mental health care.
METHODS: Actigraphy monitoring was completed for 5-23 days in 250 participants (aged 12-30) presenting to youth-focused early intervention services in Sydney, Australia. Participants were followed longitudinally as part of the Optymise cohort for 6+ months (up to 8 years; median 2.5 years). Logistic regression and Cox proportional hazard models estimated associations between SCRDs and illness progression, after controlling for relevant baseline clinical and demographic covariates (e.g., age, sex, social and occupational functioning, mania-like and psychotic-like experiences, medication use).
RESULTS: Longer sleep duration at baseline predicted higher odds of transition (OR = 2.23 [95%CI = 1.38-3.74]), and shorter time-to-transition (HR = 2.05 [95%CI = 1.23-3.40]) to full-threshold bipolar or psychotic disorders. This effect remained significant after controlling for clinical covariates. Later sleep midpoint predicted transition to any full-threshold mental disorder (OR = 1.46 [95%CI = 1.02-2.17]) at the uncorrected significance level.
CONCLUSIONS: Excessive sleep duration may represent an early marker of vulnerability for progression to severe mental illness. Findings support the prognostic utility of objective measures of SCRDs to guide indicated prevention and early intervention.
