Advancing the Prevention of Severe Mental Illness: Insights and Future Directions from a Public Health Perspective

Dear Editor,

We read with great interest the article by Zheng et al. titled “Physical Activity, Sleep, and Risk of Late-Onset Severe Mental Illness: A Prospective Cohort Study From UK Biobank.”¹ This study is the first to evaluate the joint association between physical activity (PA) and sleep with the risk of late-onset severe mental illness (SMI), and it holds significant practical implications. The findings suggest that low and moderate levels of PA, as well as poor sleep, are each independently associated with an increased risk of SMI. Moreover, the study identified a significant additive and interactive effect between PA and sleep on the risk of late-onset SMI. Individuals with both low PA levels and poor sleep quality were found to be at an even higher risk of developing late-onset SMI. These findings provide valuable insights for public health interventions and the clinical management of patients with SMI. However, we would like to offer several suggestions for consideration.

Although the study employed a Cox regression model to examine causal relationships, the possibility of reverse causality cannot be fully excluded. In particular, the early onset of SMI may influence individuals’ sleep patterns and physical activity levels. That is, the development of SMI could alter patients’ sleep behaviors and physical activity, complicating the determination of the directionality of the association. Future studies should adopt more rigorous methodological designs to minimize the potential impact of reverse causality and enhance the validity of the findings.

Second, future studies may consider including sedentary time as a variable to explore the relationship between adherence to the 24-hr movement guidelines and the risk of SMI.² This approach would contribute to a more comprehensive understanding of how combinations of physical activity, sedentary behavior, and sleep affect SMI risk, thereby providing a stronger scientific basis for public health interventions.

In addition, we recommend applying group-based trajectory modeling to classify the longitudinal patterns of change in metabolic equivalents of task and sleep scores during the follow-up period. Group-based trajectory modeling has been successfully employed in numerous studies to analyze changes in health-related behaviors and is effective in identifying distinct dynamic patterns within populations.^3,4 This method allows for the identification of subgroups exhibiting similar trajectories—such as persistently high or low levels, or increasing/decreasing trends—thereby facilitating the exploration of associations between different behavioral trajectories and the risk of SMI.

Finally, we thank the authors for providing compelling evidence in this field, highlighting the pivotal role of physical activity and sleep in the prevention of late-onset SMI. From a public health perspective, targeted interventions to improve physical activity levels and sleep quality in the general population are warranted. On one hand, health education programs should be implemented to raise public awareness of the importance of physical activity and adequate sleep, alongside financial support or access to free exercise facilities for economically disadvantaged groups. On the other hand, healthcare institutions should strengthen long-term follow-up for high-risk populations, offering individualized guidance on exercise and sleep hygiene to promote consistent physical activity and high-quality sleep patterns. These efforts may ultimately improve quality of life and reduce the risk of SMI.

Funding

None declared.

Conflicts of Interest

The authors have declared that there are no conflicts of interest in relation to the subject of this study.