Abstract
This longitudinal study examined the predictive role of emotion reactivity and regulation on sleep quality across early to middle childhood. Participants were typically developing Swedish children (N = 116, 49% girls), with reactivity and regulation assessed at ages 3, 6 and 9 years, and sleep quality measured at the age of 9 years. Results provided partial support for preregistered hypotheses. Regulation was consistently associated with sleep quality, with concurrent regulation at the age of 9 years showing the strongest association. Reactivity only correlated with sleep quality at the age of 9 years. Exploratory path analysis showed more complex patterns. Regulation emerged as the most consistent predictor of better sleep quality. Early reactivity (ages 3 and 6 years) showed small positive links to later sleep, whereas higher concurrent reactivity at the age of 9 years predicted poorer sleep quality. Mediation analyses suggested that regulation may serve as a mechanism linking reactivity to later sleep quality. Together, these findings underscore both the developmental value and the complexity of emotion–sleep relations, highlighting the need for nuanced, context-sensitive approaches to understanding how emotional functioning supports children’s sleep health.