LAUSR

Depression and poor sleep quality commonly co‐occur with autism, and depression has been associated with loneliness and reduced social support. In non‐autistic samples, poor sleep quality and daytime fatigue also contribute to depression. However, the contribution of sleep quality and fatigue to depressive symptoms, and how they interact with social factors to influence depression in autism remain unexplored. Our aim was to examine these relationships in 114 young autistic adults aged 15–25 years (57% male) from the SASLA online, longitudinal study (baseline and 2‐year follow‐up). Hierarchical multiple regression models examined the association between social well‐being (social integration and social contribution; T1), sleep quality (T1, T2), and fatigue (T1, T2) on depression (T1, T2). Two mediation models were conducted on T1 data predicting depression from sleep quality though fatigue and sleep quality through social well‐being. Depression and fatigue scores did not change over 2 years, but sleep quality worsened. The T1 regression model was significant (R2 = 36%) with fatigue and social contribution individually predicting depression symptomatology. The longitudinal regression model was also significant (adjusted R2 = 57%) with social contribution (T1) as the only significant predictor of depression (T2). Fatigue trended towards mediating the sleep quality–depression relationship, while social well‐being was a significant partial mediator of this relationship. Results highlight that sleep quality, fatigue, and social well‐being contribute to depression among young autistic adults. Interestingly, fatigue and social well‐being were independently associated with depression. Thus, addressing sleep quality and associated fatigue, and social well‐being is important when treating depression in autistic individuals.