Unhealthy lifestyle behaviors are prevalent among people with mental illness (MI), affecting their physical and mental health. Most research has focused on the isolated effects of lifestyle behaviors, leaving the interconnectedness between these behaviors and health outcomes unexplored. This study aimed to examine these relationships and identify the most strongly connected lifestyle behavior or health outcome within a network.

We conducted a cross-sectional study with 423 inpatients with MI, receiving care as usual. Lifestyle behaviors, physical and mental health outcomes were assessed through questionnaires and routine data. A Gaussian Graphical Model was estimated, and strength centrality was calculated to identify the most influential nodes.

Mean age was 55.5 years, 42% were female, and 41% were diagnosed with schizophrenia. Psychological and physical quality of life (QoL), nighttime sleep problems, and overall sleep quality were the most strongly connected nodes. Sleep was strongly associated with physical QoL. Furthermore, there were negative associations between healthy food intake and cholesterol ratio, and positive associations between daily doses of antipsychotics and length of hospital stay. Node strength was stable (CS(cor = 0.7) = 0.75). No clear pattern emerged among other lifestyle behaviors and health outcomes.

This study offers insights into the interrelatedness of lifestyle behaviors and health outcomes. Addressing sleep problems could enhance QoL and potentially influence other health outcomes. Psychological and physical QoL were also strongly associated, emphasizing the importance of perceived well-being in health outcomes. Future research could explore causal pathways to identify treatment targets to improve care.