Daily Associations Between Sleep Parameters and Depressive Symptoms in Individuals with Insomnia: Investigating Emotional Reactivity and Regulation as Mediators.

OBJECTIVES Previous research suggests that insomnia and depressive symptoms might be causally related. Emotional reactivity and regulation have been proposed to explain the potential causal relationship between insomnia and depression. However, longitudinal evaluations of their mediating effects are limited. Hence, the current study aimed to examine the mediating effects of emotional reactivity and regulation on the longitudinal associations between daily sleep parameters and depressive symptoms over 14 days in individuals with insomnia. METHODS Participants were sixty adults aged 18-65 who had clinically significant insomnia. They filled out a survey each morning and evening and wore actigraphy watches for 14 consecutive days. The five sleep parameters were measured by sleep diary in the morning survey (subjective total sleep time, subjective sleep efficiency, and sleep quality) and actigraphy watches (objective total sleep time and objective sleep efficiency). Emotional reactivity and emotion regulation strategy use during the day were assessed in the evening survey using the International Positive and Negative Affect Schedule Short Form, Emotion Regulation Questionnaire, and Cognitive Emotion Regulation Questionnaire. Depressive symptoms of the day were evaluated in the evening survey with the Center for Epidemiologic Studies Depression Scale. RESULTS Results showed that sleep quality and depressive symptoms, as well as actigraphy-measured sleep efficiency and depressive symptoms, predicted each other in individuals with insomnia, mediated by negative reactivity but not emotion regulation. CONCLUSIONS The present findings support the mediating role of negative emotional reactivity in the bidirectional, daily relationship between sleep parameters and depression in individuals with insomnia.