Background The prevalence of suboptimal health status has been increasing worldwide, posing a significant challenge to public health. Meanwhile, family health has been recognised as an important factor influencing individual health outcomes. However, the mechanisms through which family health affects suboptimal health status remain unclear. We aimed to investigate the parallel mediation role of sleep quality and health behaviour in the relationship between family health and suboptimal health status.

Methods We conducted a cross-sectional online survey with a sample of adults?>18 years old from four provinces in China. The survey questionnaires queried their demographic characteristics, family health, suboptimal health status, sleep quality, and health behaviour. We assessed family health by the Family Health Scale-Short Form and suboptimal health status using the Suboptimal Health Status Questionnaire. We employed structural equation modelling to analyse the data and test the proposed mediation model.

Results we collected 4918 valid questionnaires. The mean age of the participants was 30.1 years (standard deviation=12.5). The correlation analysis demonstrated a significant negative association between family health and suboptimal health status (r=−0.44; P<0.001). The results of the parallel mediation analysis showed that family health had a significant indirect effect on suboptimal health status through both sleep quality (β=-0.350; P<0.001) and health behaviour (β=−0.137; P<0.001). The total indirect effect of family health on suboptimal health status through both sleep quality and health behaviour was also significant (β=−0.569, P<0.001).

Conclusions This study highlights the significance of family health as a predictor of suboptimal health status and suggests that sleep quality and health behaviour are parallel mediators in this relationship. By understanding the role of family health, sleep quality, and health behaviour, interventions can be targeted to improve overall health outcomes.