Emotional inertia is independently associated with cognitive emotion regulation strategies and sleep quality.

Emotional inertia (i.e. the tendency for emotions to persist over time) is robustly associated with lower wellbeing. Yet, we know little about the mechanisms underlying this relationship. Good quality sleep and frequent use of adaptive cognitive emotion regulation (CER) strategies reduce the persistence of negative affect (NA) over time. However, whether sleep and adaptive CER strategy use work in concert to reduce NA inertia is unclear. In the current study, participants (N = 245) watched a series of film clips and rated how each clip made them feel on negative and positive affective states. Emotion ratings were collected again after a short rest period to determine the persistence of clip-induced affect. Standardised questionnaires were used to index participants' sleep quality and tendency to engage in adaptive CER strategies. Autoregressive models demonstrated that better sleep quality was associated with lower NA inertia (d = 0.25). This association also held when controlling for mean and variability of NA. Interestingly, the association between adaptive CER strategy use and NA inertia was observed irrespective of whether sleep quality was good, average, or poor (d = 0.13). These findings suggest that sleep and adaptive CER strategies hold independent rather than interdependent roles in maintaining emotional wellbeing.