(PS1-83) Associations Between Chronotype, Rumination, Depressive Symptoms, and Sleep

Abstract Text: Chronotype, an individual’s typical sleep and wake times, has been consistently associated with poor mental health with evening-types often reporting greater depressive symptoms than morning-types. Rumination is also well established as both contributing to and maintaining depressive symptoms. Eveningness and rumination are both associated with poor sleep characteristics such as increased sleep onset latency and poor sleep quality. However, little research has investigated the relationship between chronotype and rumination and subsequent associations with depressive symptoms and sleep. The current study sought to examine relationships between chronotype, rumination, depressive symptoms, and sleep. Undergraduates (N = 146) completed self-report measures of chronotype, depressive symptoms, and rumination. Depressive symptoms and rumination were also measured at two-week and three-month follow-ups. In addition, participants completed measures of rumination, positive and negative affect, and sleep (e.g. sleep onset latency, sleep quality, wake and sleep times) daily over two weeks of ecological momentary assessment in between baseline and two-week follow-up. Self-reported chronotype at baseline closely aligned with daily sleep and wake times (B = –.07, p < .001). Linear regression analyses revealed that, accounting for biological sex, eveningness was associated with greater rumination concurrently (B = –.09, p = .013), but not at the three-month follow-up (B = –.07, p = .100). Accounting for rumination, eveningness was associated with greater depressive symptoms both concurrently (B = –.29, p = .005) and at two-week follow-up (B = –.45, p < .001), but not at three-month follow-up (B = –.11, p = .288). Rumination was related to greater depressive symptoms concurrently (B = 1.82, p < .001) and prospectively at two-week (B = 1.64, p < .001) and three-month (B = 2.37, p < .001) follow-ups. Linear mixed model analyses revealed that, accounting for biological sex, morningness was associated with greater positive affect in the morning (B = .17, p < .001) and evening (B = .16, p = .003), while eveningness was associated with greater nighttime rumination (B = –.04, p = .031) and longer sleep onset latency (B = –.01, p = .025). Interestingly, eveningness was not associated with negative affect in the morning (B = –.06, p = .118) or evening (B = –.04, p = .193). Rumination was associated with lower positive affect in the evening (B = –.30, p < .001) but not the morning (B = –.01, p = .918), greater negative affect in the morning (B = .87, p < .001) and evening (B = 1.08, p < .001), and poorer sleep quality (B = –.03, p = .001). These results support the influence of chronotype and rumination on depressive symptoms and sleep and suggest that chronotype and rumination may have distinct effects on sleep. While further research is necessary, nighttime rumination in particular may be a potential target for intervention among evening-types with elevated depressive symptoms and sleep problems.