Negative interpretation bias and repetitive negative thinking as mechanisms in the association between insomnia and depression in young adults

Despite evidence supporting sleep's role in the development and maintenance of depression, mechanisms underlying this association in young people are less established. Negative interpretation bias (the tendency to interpret ambiguous situations negatively) and repetitive negative thinking (RNT) are important candidate mechanisms. Whilst negative interpretation bias is implicated in depression development, it is a transdiagnostic process and may result from insomnia. Yet, research relating to these constructs is lacking. RNT is another transdiagnostic process implicated in association between negative interpretation bias, depression and insomnia. However, an elaborated model that includes both mechanisms is yet to be tested. It was hypothesised that negative interpretation bias and RNT would sequentially mediate the relationship between sleep/insomnia and depressive symptoms in young people. The associations predicted by this hypothesis were tested via cross-sectional mediation in a sample of 214 participants (Mage = 19.19 years, SD = 1.67, Rangeage = 17-24 years, 20% male). Participants completed questionnaire measures of insomnia symptoms, depression symptoms and RNT, an ambiguous scenarios task and a 1-week sleep diary. Results were consistent with negative interpretation bias and RNT as sequential mechanisms which partially account for the relationship between sleep (i.e., insomnia severity and sleep parameters) and depression. This study supports negative interpretation bias and RNT as mechanisms linking insomnia and depression in young people, as the predicted associations between these variables were observed. Future research should investigate the causal/directional associations. However, results support theoretical models, and suggest sleep, interpretation bias and RNT may be important processes to target in preventing and treating depression.