Actigraphy-derived circadian rhythms, sleep-wake patterns, and physical activity across clinical stages and pathophysiological subgroups in young people presenting for mental health care.

Staging models for youth mental health aim to locate clinical presentations on a spectrum from at-risk states to persistent disorder and predict future illness trajectories. Our previous publications on trans-diagnostic staging proposed three pathophysiological subgroups of major mood or psychotic disorders in youth ('hyperarousal-anxious depression', 'circadian-bipolar spectrum', 'neurodevelopmental-psychosis'). This study aims to investigate differences in objective measures of 24hr sleep-wake patterns, circadian rhythms, and physical activity across clinical stages and pathophysiological subgroups. Actigraphy data (median: 13 days) was collected from 497 youth presenting for mental health care (21.6 ± 4.7 years, 37% male) and 88 controls (24.1 ± 3.8 years, 44% male). Actigraphy estimates were compared across groups using analysis of covariance adjusting for age and sex. Compared with controls or earlier clinical stages, later clinical stages were significantly associated with longer sleep duration(η = 0.04), later sleep midpoint(η = 0.02), lower sleep regularity(η = 0.02), lower relative amplitude of the rest-activity cycle(η = 0.05), higher interdaily stability(η = 0.03), lower total activity(η = 0.08) and less moderate-vigorous physical activity(η = 0.06). Compared to controls, the 'circadian-bipolar spectrum' subgroup had later sleep midpoint(η = 0.02), and higher interdaily stability(η = 0.03); the 'neurodevelopmental-psychosis' subgroup had longer sleep duration(η = 0.02), and lower total activity(η = 0.03); and the 'hyperarousal-anxious depression' subtype had later sleep midpoint(η = 0.02), and lower sleep regularity(η = 0.02). The findings suggest differences in sleep-wake and rest-activity patterns according to clinical stage and proposed illness trajectory subtypes. The cross-sectional associations of sleep regularity and physical activity with clinical stage highlight a need for longitudinal explorations of how sleep-wake patterns and circadian rhythms interact with treatment factors and progression of both mental and physical illness.