Theoretical models of insomnia disorder recognise an emotional component in the maintenance of the disorder. Nonetheless, the field of emotions is vast and different processes are involved in psychological well-being. The present narrative review focusses on emotion regulation and affect dynamics, synthesising some of the most recent and relevant evidence on emotions in relation to the quality of sleep and to insomnia disorder. The literature underlines the close association between impaired sleep quality and difficulties in regulating emotions. Impaired sleep quality is also associated with reduced positive affect and increased negative affect, but little evidence supports a bi-directional association between affective states and sleep. Affect variability in relation to sleep has been less investigated. Initial evidence suggests that high variability in positive affect has a negative impact on sleep. Neurobiological and behavioural evidence indicates that insomnia disorder is associated with emotion dysregulation, negative affect, and a distinct daily profile of affective states. More research is needed on the affective experience of patients with insomnia disorder, adopting multiple sampling of affect across the day and the week. Understanding how the unfolding of emotions over time interact with sleep alterations may help to improve the tailoring and monitoring of treatments addressing disturbed emotional processes in insomnia disorder.
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