Autistic individuals experience a heightened risk of depression and lower quality of life; however, the biological underpinnings for this increased risk remain to be fully established. We assessed whether disruption of self-reported sleep and circadian factors mediates the associations of autistic traits with depression symptom severity and quality of life in a community-based survey study. A total of 838 participants (mean: 52.8 [SD = 1.3] years, 70 % females) from a large-scale observational survey completed the Autism Quotient Scale, Hospital Anxiety and Depression Scale, Cantril Ladder quality of life, Insomnia Severity Index, Pittsburgh Sleep Quality Index, and the Munich Chronotype Questionnaire. Higher autistic traits were significantly associated with higher depression symptom severity (p = 0.04) and significantly lower quality of life (p < 0.001). Insomnia severity and later chronotype partly mediated the association of autistic traits and depression symptom severity (respectively, β = -0.02, 95 % CI -0.03, -0.01; β = -0.02, 95 % CI =[-0.04, -0.01). Likewise, insomnia severity and later chronotype partly mediated theassociation of autistic traits with lower quality of life (respectively, β = - 0.09, 95 % CI -0.14, -0.02; β = -0.05, 95 % CI = -0.09, -0.01). Our findings indicate that autistic traits are associated with higher depression severity and lower quality of life, mediated by insomnia and chronotype. Future studies targeting insomnia complaints and later chronotype in autistic people may help alleviate their mental health complaints and increase quality of life.
