The Transactional Role of Rapid Eye Movement Sleep in Undergraduates' Day-To-Day Positive and Negative Mood.

The current study sought to elucidate the interplay of the mutually influencing processes of daily mood and REM sleep, a stage of sleep hypothesised to be involved in affect change. Young adult college students (N = 156; Mage = 20.3 years, SD = 3.2; 77.6% female) completed a baseline online survey followed by wearing an ambulatory EEG headband overnight and completing daily morning and evening mood surveys for 10 consecutive days. Results, based on dynamic structural equation modelling, demonstrated a bidirectional relationship between evening negative mood and REM sleep minutes such that decreases in the minutes of the prior night's duration of REM sleep predicted relative increases in the levels of negative mood the following evening and vice versa. In addition, REM duration mediated the effect of the prior evening's negative mood on the following morning's positive mood such that increases in evening negative mood predicted relative decreases in REM minutes, which, in turn, predicted decreases in morning positive mood. Results from the current study highlight the critical role of REM sleep for emotional well-being as well as the importance of mood regulation before sleep.