Associations of fatigue and sleep disturbance with nine common mental disorders

To investigate the contribution of nine mental/substance use disorders to fatigue and sleep disturbance.

3620 Australians aged 18 years or older recruited from the general community via Facebook during January-February 2016 completed an online survey assessing demographic characteristics, diagnosed medical conditions and nine mental disorders. Outcome measures were Patient Reported Outcomes Measurement Information System (PROMIS®) fatigue and PROMIS sleep disturbance.

Overall, 56% of the sample met criteria for at least one mental disorder. Linear regression models of sleep disturbance revealed all mental disorders except obsessive compulsive disorder (β = 0.038) had independent associations with sleep disturbance, with generalised anxiety disorder (GAD) (β = 0.173), major depressive disorder (MDD) (β = 0.117) and post-traumatic stress disorder (PTSD) (β = 0.111) making the greatest contribution. Inclusion of fatigue in the model attenuated the effects of panic disorder, MDD and attention-deficit hyperactive disorder (ADHD) to non-significance. For the outcome of fatigue, GAD (β = 0.223), MDD (β = 0.176) and PTSD (β = 0.147) made the greatest contributions, although all disorders had significant independent relationships. After adjusting for sleep disturbance, all mental disorders continued to make a significant contribution except for alcohol use disorder and substance use disorder.

Sleep disturbance and fatigue have independent associations with many mental disorders after correcting for comorbidity and known confounds. The disorders providing the greatest contribution to sleep disturbance and fatigue were GAD and MDD. Sleep disturbance and fatigue may be appropriate transdiagnostic targets for improving symptoms and global functioning for people with mental disorders.