P153 Sleep timing and chronotype in perinatal periods: Longitudinal changes and associations with wellbeing from pregnancy to 2 years postpartum

Abstract Introduction Significant changes to sleep occur during perinatal periods. Existing research focuses on duration and quality, but not timing or chronotype. This study investigated change trajectories of chronotype from late pregnancy two years postpartum, examined associations between insomnia, sleep-related impairment, mood at seven different time-points. Methods Data were a 2-arm randomised controlled trial testing behavioural diet interventions. A community sample nulliparous females without severe sleep/mental health conditions participated. Participants self-reported bedtime, rise-time, (short Morningness-Eveningness Questionnaire), Insomnia Severity Index, PROMIS Depression, Anxiety, Sleep-Related Impairment over time points: gestation weeks 30 35, postpartum months 1.5, 3, 6, 12 24. Results 163 participants (mean age 33.4±3.4 years) took part. Mixed effects models adjusting for group allocation showed that both bed- rise-times became progressively earlier by approximately 20–30 minutes (p<.001); shifted towards more morningness (p<.01). After covariates (sleep efficiency, mental history, social support, age, allocation), greater was significantly associated with lower symptoms insomnia impairment (p-values<.001); each time-point, depression anxiety non-significant (p-values>0.65). Conclusions Sleep the first years. Greater less complaints daytime period. The mechanisms these findings may be through further research.