Sleep–wake cycle phenotypes in young people with familial and non-familial mood disorders

Objectives: Converging evidence identifies that the offspring of parents with bipolar disorder (BD), individuals at clinical high risk of BD, and young people with recent onset BD may differ from other clinical cases or healthy controls in terms of sleep–wake profiles. However, it is possible that these differences may reflect current mental state, subtype of mood disorder, or familial traits. This study aimed to determine objective and subjective sleep–wake profiles in individuals aged 15–25 years with a current major depressive episode, in relation to familial traits. Methods: Frequency matching was employed to ensure that each individual with a confirmed family history of BD (FH+) could be compared to four controls who did not have a familial mood disorder (FH–). Pre-selected objective actigraphy and subjective Pittsburgh Sleep Quality Index (PSQI) ratings were compared using one-way analysis of variance (ANOVA) and applying the Benjamini–Hochberg (BH) correction for false discoveries. Results: The sample comprised 60 individuals with a mean age of 19 years. The FH+ (n=12) and FH– groups (n=48) differed on three key sleep parameters: mean sleep duration on week nights (P=.049), variability in waking after sleep onset (P=.038), and daily disturbances (PSQI dimension of sleep disturbance and daytime dysfunction; P=.01). Conclusions: The sleep profiles we identified in this study, especially the daily disturbances phenotype, provide support for research into endophenotypes for BD. Also, the findings may offer the opportunity for more tailored, personalized interventions that target specific components of the sleep–wake cycle in individuals with a family history of BD.