Chronotype, sleep quality, depression and pre-sleep rumination: A diary and actigraphy study.

Eveningness has been associated with both disturbed sleep and depression. It is unclear, however, if deprived sleep explains evening types' vulnerability to depression. The role of pre-sleep rumination in these associations also remains understudied. The present study assessed the relationship between eveningness and sleep quality, as well as the possible mediating effect of pre-sleep rumination and the moderating effect of a history of depression, under naturalistic conditions. Eighty-eight Dutch-speaking participants (87.5% females, 21.4 ± 3.7 years) were selected on the basis of their non-intermediate chronotype using the Morningness Eveningness Questionnaire (evening types (n = 53); morning types (n = 35)). Depression status was assessed through a diagnostic interview (healthy (n = 61); remitted depressed (n = 27)). Participants' sleep characteristics were monitored via actigraphy and sleep diaries for seven consecutive days and nights. Pre-sleep rumination was measured via a self-report questionnaire. Evening types had longer subjective and actigraphic sleep onset latency than morning types. Pre-sleep rumination did not mediate the former associations but predicted longer subjective sleep onset latency. Furthermore, the relationship between chronotype and subjective sleep onset latency was moderated by depression history. Remitted depressed evening types reported longer sleep onset latency than healthy evening and morning types, possibly posing the former at a higher risk for depressive relapse. Overall, the current findings address the need to further investigate the physiological signature of circadian rhythms and sleep latency. This could serve as a foundation for the development of prevention and early intervention programs, tailored for mood and sleep disorders.