Introduction: Adolescence is a period of vulnerability for emotion regulation and sleep difficulties, risks that might be compounded by intense COVID-19 lockdowns and challenges. The aim of this study was to investigate how sleep quality related to emotion regulation difficulties in adolescents during lockdown in Perú. Methods: Participants were 2563 adolescents enrolled in Innova school in Perú (11 – 17 years) in May 2020. Hypotheses were derived from exploring one half of the sample, preregistered at https://osf.io/fuetz/, and then confirmed in the second half of the sample. Participants completed subjective surveys of sleep quality (short PSQI) and the Difficulties in Emotion Regulation Scale Short Form (DERS-SF). Results: Worse sleep quality was robustly associated with more difficulties in emotion regulation across both samples. The association was found particularly for emotional regulation subscales related to the ability to engage in goal directed behavior in the face of distress, emotional clarity and strategies to deal with feeling distressed. In contrast, there was no robust association between sleep and the ability to regulate impulses in the context of negative emotions, and no association with the ability to accept emotions. Girls and older adolescents robustly endorsed worse sleep quality and more difficulties in emotion regulation. Limitations: The cross-sectional nature of this study prevents us from determining the direction of the association. Data was collected using adolescent self-report which, while informative of adolescent perceptions, might diverge from objective measures of sleep or emotion regulation difficulties. Conclusions: Our findings with adolescents in Perú contribute to our understanding of the association between sleep an emotion regulation at a broader global scale.

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