Sleep well, feel well and vice versa? A meta-analysis of daily bidirectional within-person associations between sleep and affect

This meta-analysis examines the bidirectional within-person association between sleep and affect using data from 118 studies. Focusing on intensive longitudinal designs such as daily diaries and ecological momentary assessments, this meta-analysis examines how daily variations in sleep, measured via subjective and objective methods, are associated with fluctuations in positive and negative affect. Results show small-to-moderate within-person correlations, with better subjective sleep quality and longer sleep duration predicting improved next-day affect. Conversely, more positive affect and less negative affect during the day were modestly associated with better subjective sleep quality but not total sleep time. The within-person correlations were generally stronger when aspects of sleep were self-reported rather than objectively measured, highlighting the importance of perceived sleep experiences. These findings were largely consistent across age groups and health status, suggesting that the relationship between sleep and affect may be universal. Overall, this study underscores the psychological significance of everyday sleep-affect dynamics.