Volunteer participation differentially moderates the association between insomnia and poor subjective well-being in community-dwelling older adults: the Yilan study, Taiwan

OBJECTIVES: We aimed to elucidate the moderating effect of volunteer participation on the association between insomnia and subjective well-being. METHODS: This was a community-based, cross-sectional study that targeted community-dwelling older adults aged ≥ 65 years in Yilan city, Taiwan. Whether individuals had volunteered in the past month was asked. Insomnia was measured using the Athens Insomnia Scale-5. Subjective well-being was evaluated using self-rated health, self-rated happiness, the physical component summary (PCS), and the mental component summary (MCS) of Short-form 12. Interaction terms between volunteer participation and insomnia were examined to test the moderating effect of volunteer participation on subjective well-being. RESULTS: In total, 3,875 participants were included in the study. After controlling for confounders, older adults with insomnia were more likely to have poor subjective well-being, except with respect to PCS. By contrast, volunteering was associated with a low risk of association between self-rated health and happiness. The interaction terms for volunteering with self-rated happiness (p = 0.03) and the MCS (p = 0.02) were significant. The association between insomnia and poor self-rated happiness among volunteers (odds ratio [OR] = 3.91, 95% confidence interval [CI] = 1.85–8.28) was significantly stronger than that in non-volunteers (OR = 1.48, 95% CI = 1.18–1.86). However, insomnia was linked with poor MCS in non-volunteers (OR = 1.53, 95% CI = 1.21–1.94), but not in volunteers (OR = 0.64, 95% CI = 0.27–1.50). DISCUSSION: Volunteer participation moderated the association between insomnia and subjective well-being; specifically, volunteering strengthened the association between insomnia and poor self-rated happiness but mitigated the relationship between insomnia and poor MCS. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12877-022-03004-8.