Moving from traits to states: Examining the bidirectional day-level associations between personality states and sleep characteristics

Big-5 personality traits are robustly associated with sleep. Most theorizing points to day-level bi-directional processes; however, few studies have examined associations between personality traits and sleep at the day-level. To do so ecological momentary assessments were used in four studies (Study 1 N = 330 university students over 10 days, Study Two N = 342 community residents over 10 days, Study Three N = 458 older adults over 7 days, Study Four N = 118 undergraduate students over 7 days with personality state ratings up to 6 times a day) to conduct multilevel structural equation models examining bi-directional associations between personality states and sleep characteristics. Findings demonstrated that multiple sleep characteristics consistently predicted next day state neuroticism, conscientiousness, and extraversion, and that poor subjective sleep quality and daytime tiredness consistently predicted all Big-5 personality states. In contrast, personality states during the day had little to no consistent relation to sleep characteristics, even when examining personality states occurring in closer proximity to sleep. These findings highlight the importance of sleep for personality but challenge theorizing that personality traits shape sleep because of day-level personality processes. Findings also highlight future work needed to better understand why personality and sleep are related.