Daily associations between sleep and urgency, and variation by risk for developing bipolar disorder

Abstract

Background. Sleep has been widely associated with negative mental health outcomes and has been considered a key feature of mood disorders, bipolar disorder in particular. Previous work has found that aspects of sleep health, such as perceived sleep quality and sleep-wake rhythms, may predict and be predicted by emotional impulsivity (i.e., urgency) to varying degrees, though few studies have explored this association on a daily level. What is yet to be explored is the bidirectional nature of these associations on a daily level, and the extent to which these associations may differ for those at higher risk for developing bipolar disorder. Aims. The present study examined the associations between urgency, sleep quality, and sleep-wake rhythms as they unfold in daily life and extended past work by exploring differential associations based on risk for bipolar disorder. It was hypothesized that worse sleep quality and greater sleep-wake rhythm irregularity would exhibit bidirectional associations with higher urgency on within-person and between-person levels, and that these associations would be stronger in participants at greater risk for developing bipolar disorder. Method. The present study used data collected from a larger ecological momentary assessment (EMA) protocol in a community sample of young adults (n = 495). Participant self-reports on an initial baseline survey and 8 weekends of surveys collected 5 times per day were used to test hypotheses. Multilevel models were used for confirmatory analyses and for additional exploratory analyses aiming to distinguish among aspects of sleep quality and whether these associations held specifically for groups that are disproportionately impacted by sleep disturbances. Results. Within- and between-person associations between sleep quality and urgency were supported in both directions, though only between-person associations were detected for the sleep-wake rhythm variables. The two variables measuring sleep-wake rhythm irregularity yielded inverse results, with higher sleep duration irregularity predicting higher urgency and higher sleep midpoint irregularity predicting lower urgency, contrary to hypotheses. These associations were not moderated by risk for bipolar disorder. Exploratory analyses revealed that specific types of sleep quality disturbance showed associations with urgency that mirrored urgency’s association with general sleep quality disturbance. There were some differences in sleep-urgency associations based on race, gender identity, and sexual orientation. Conclusions. Urgency may be more tightly tied to sleep quality than to sleep-wake rhythms on the daily level, and the inconsistent between-person associations with sleep-wake rhythms may warrant further investigation. Thus, improving sleep quality may be a more effective clinical target than regulating sleep-wake rhythms for some individuals. Finally, the comparatively stronger associations between sleep health and urgency that are seen in bipolar disorder may not emerge until after disorder onset, which has important implications for early intervention strategies as well as theories of the etiology of bipolar disorder.