Investigating the cognitive mechanisms by which sleep supports emotion regulation and mental health

Sleep plays an important role in how we process and deal with our emotions on a daily basis. As emotion regulation difficulties are a key predictor of poorer mental health, understanding the mechanisms by which sleep supports emotion regulation and mental health is of the upmost importance to further our understanding of psychiatric vulnerability. This thesis aims to investigate the cognitive mechanisms by which sleep supports emotion regulation and mental health. Specifically, three components of emotion regulation are examined: cognitive emotion regulation (CER), emotional reactivity, and emotional inertia. The first empirical chapter (Chapter 2) investigates whether the benefits of adaptive CER strategies (to lower depression and anxiety) are contingent on high sleep quality. The second empirical chapter (Chapter 3) examines whether sleep deprivation (versus a night of sleep) influences the evolution of arousal responses during exposure to ambiguous threat, as well as the reciprocal influence of slow wave activity (SWA) on affect regulation. The third empirical chapter (Chapter 4) explores whether the benefits of adaptive CER strategy use (to lower emotional inertia) are contingent on high sleep quality. Our findings suggest that: 1) greater use of adaptive CER strategies and high sleep quality independently promote resilience to depression, 2) a night of sleep (versus sleep deprivation) promotes the regulation of affect in response to prolonged ambiguous threat; however, SWA is not associated with this regulation, and 3) greater use of adaptive CER strategies and high sleep quality independently reduce the persistence of negative emotions over time. In light of these findings, cognitive control is proposed as one critical mechanism underlying the association between sleep and emotion regulation. Altogether, this thesis provides important insights into the cognitive mechanisms by which sleep supports emotion regulation, and mental health, and points towards modifiable mechanisms that may buffer against psychiatric vulnerability.