Sleep disturbances and functional impairment in severe mental illness: A structural equation modeling study

Sleep disturbances are highly prevalent in individuals with severe mental illness (SMI) and are associated with functional impairment. This study examined the prevalence of sleep disturbances and their associations with psychiatric symptoms and functional outcomes in a transdiagnostic SMI sample.

In this cross-sectional study, SMI outpatients completed standardized assessments of sleep disturbances (PSQI, ISI, STOP-Bang, ESS, SQ-RLS, and SQ-RBD), psychiatric symptoms (HARS, MADRS, YMRS, PANSS-N, and CGI-S), and functioning (FAST). Bivariate analyses were followed by structural equation modeling (SEM), including latent constructs for insomnia and depressive/anxious symptoms to estimate direct and indirect associations with functional impairment.

A total of 229 participants were included, and 69% screened positive for at least one sleep measure, including poor sleep quality (55.5%). Among the specific sleep-related problems, high risk of obstructive sleep apnea (OSA) (45.8%) was the most prevalent. Sleep disturbances were associated with greater clinical severity and worse functional impairment. In the SEM, depressive/anxious symptoms (β = 0.45), negative symptoms (β = 0.38), manic symptoms (β = 0.17), and OSA risk (β = 0.41) were independently associated with functional impairment. Insomnia exhibited an inconsistent pattern, with a negative direct effect (β = -0.47) and a positive indirect effect on functional impairment through depressive/anxious symptoms (β = 0.22).

Sleep disturbances are highly prevalent in individuals with SMI and are associated with functional outcomes, particularly insomnia and OSA risk. Systematic screening for sleep disturbances in psychiatric care may help identify clinically relevant and potentially modifiable factors associated with functional impairment.