Insomnia has been repeatedly associated with elevated CRP through large longitudinal and experimental studies.6 Furthermore, both sleep disturbance and inflammation have been shown to be influence the risk of depression.32 The association between elevated CRP and anxiety symptoms in depression is also well established.6 It should be noted, however, that this association only just met cut-offs for significance in our analysis, with a wide 95% CI indicating low precision (95% CI 1.39–21.7, P = 0.044). Here, CRP is linked to depressive symptom measurement.