Prevalence of insomnia symptoms and mediation of the association between multimorbidity and insomnia symptoms by loneliness and multisite pain among middle-aged and older adults in Malaysia

The aim of the study is to estimate the prevalence and associated factors of insomnia symptoms among middle-aged and older adults in Malaysia. In all, 5602 cross-sectional nationally representative data from adults (≥40 years) of the 2018 Malaysia Aging and Retirement Survey (MARS) was analyzed. Insomnia symptoms were assessed with three items from the Jenkins Sleep Scale (JSS-4). Unconditional multivariable logistic regression was used to identify relationships between social and health factors and insomnia symptoms. To examine the indirect effects of multimorbidity on insomnia symptoms via loneliness and multisite pain, causal mediation analyses were conducted. The prevalence of insomnia symptoms was 29.0%. In the final adjusted model, urban residence (AOR: 1.25, 95% CI: 1.10–1.43), multisite pain (AOR: 1.18, 95% CI: 1.04–1.35), loneliness (AOR: 1.11, 95% CI: 1.08–1.14), poor self-rated health (AOR: 1.16, 95% CI: 1.11–1.22), incontinence (AOR: 1.91, 95% CI: 1.56–2.33), and multimorbidity (AOR: 1.21, 95% CI: 1.05–1.39) were positively associated with insomnia symptoms, while male sex (AOR: 0.88, 95% CI: 0.77–0.99), Islamic religion (AOR: 0.75, 95% CI: 0.66–0.86), has caring friends (AOR: 0.91, 95% CI: 0.85–0.98), and higher physical activity (AOR: 0.96, 95% CI: 0.94–0.98) were negatively associated with insomnia symptoms. Furthermore, there was a significant indirect effect of loneliness (explaining 29.2%) and multisite pain (explaining 30.3%) on insomnia via multimorbidity. Almost one in three aging adults reported insomnia symptoms. Loneliness and multisite pain were found to mediate the association between multi-morbidity and insomnia problems. Reducing loneliness and multisite pain may help in reducing insomnia symptoms in aging multi-morbid patients.