Biological Rhythms in Mood and Anxiety

Abstract

Introduction: In Major Depressive (MDD) and Bipolar Disorders (BD), there are well-documented changes in sleep and biological rhythms. However, how sleep and biological rhythm disruptions impact functioning and quality of life (QOL) in these populations, and how these disruptions affect perinatal mood and anxiety remains little-known. In this thesis, we aimed to compare sleep and biological rhythms in individuals with and without mood disorders, and to investigate whether these measures can account for worsened functional impairment and QOL in these populations. We investigated whether clinical variables combined with sleep and biological rhythms during pregnancy can be used to predict depressive and anxiety symptom severity postpartum. Finally, we investigated longitudinal changes in sleep, and biological rhythms over the perinatal period. Results: Subjective and objective sleep and biological rhythm disruptions, and light exposure differences are wide-spread in MDD and BD. Regression analyses showed that subjective and objective sleep and biological rhythm disruptions can explain 43% of variance in QOL scores, and 52% of variance in functional impairment in MDD, BD and healthy controls. Clinical and demographic variables, objective and subjective sleep and biological rhythm measures collected during pregnancy accounted for 50% of postpartum depression and 49% of postpartum anxiety symptom severity variance, in regression analyses. Numerous sleep and biological rhythm changes occurred across multiple domains from pregnancy to postpartum. Conclusion: Results suggest that sleep and biological rhythm disruptions occur across many domains in mood disorders, including sleep, light exposure, daily activity rhythms and melatonin. These disruptions are associated with worse QOL and functioning in BD, MDD and healthy controls. Biological rhythms and sleep changes across the perinatal period can be used to predict severity of postpartum depressive and anxiety symptoms. This work highlights the importance of sleep and biological rhythms as intervention targets across different outcomes, and across different mood diagnoses.