LAUSR

The COVID‐19 pandemic is a rare stressor that has precipitated an accompanying mental health crisis. Prospective studies traversing the pandemic's onset can elucidate how pre‐existing disease vulnerabilities augured risk for later stress‐related morbidity. We examined how pre‐pandemic sleep reactivity predicted maladaptive stress reactions and depressive symptoms in response to, and during, the pandemic. This study is a secondary analysis of a randomised controlled trial from 2016 to 2017 comparing digital cognitive behavioural therapy for insomnia (dCBT‐I) against sleep education (N = 208). Thus, we also assessed whether dCBT‐I moderated the association between pre‐pandemic sleep reactivity and pandemic‐related distress. Pre‐pandemic sleep reactivity was measured at baseline using the Ford Insomnia Response to Stress Test. In April 2020, participants were recontacted to report pandemic‐related distress (stress reactions and depression). Controlling for the treatment condition and the degree of COVID‐19 impact, higher pre‐pandemic sleep reactivity predicted more stress reactions (β = 0.13, ± 0.07 SE, p = 0.045) and depression (β = 0.22, ± 0.07 SE, p = 0.001) during the pandemic. Further, the odds of reporting clinically significant stress reactions and depression during the pandemic were over twice as high in those with high pre‐pandemic sleep reactivity. Notably, receiving dCBT‐I in 2016–2017 mitigated the relationship between pre‐pandemic sleep reactivity and later stress reactions (but not depression). Pre‐pandemic sleep reactivity predicted psychological distress 3–4 years later during the COVID‐19 pandemic, and dCBT‐I attenuated its association with stress reactions, specifically. Sleep reactivity may inform prevention and treatment efforts by identifying individuals at risk of impairment following stressful events.