Cancer and depression in middle-aged and elderly Chinese: The mediating role of sleep quality and the moderating role of social participation diversity - Evidence from CHARLS 2018.
Sleep quality statistically accounted for a modest portion of the cancer-depression association, and social participation diversity modified the sleep-depression association among Chinese adults aged 45 and older.
Key Findings
Results
Cancer had a significant total effect on depression among middle-aged and elderly Chinese adults.
The analytical sample included 17,550 adults aged 45 years and above from the 2018 wave of the China Health and Retirement Longitudinal Study (CHARLS).
The total effect of cancer on depression was 2.157 (95% CI: 0.458–3.856).
Depression was assessed using the 10-item Center for Epidemiologic Studies Depression Scale (CES-D-10).
Cancer was identified from harmonized and health files in the CHARLS dataset.
Results
Poor sleep quality partially mediated the relationship between cancer and depression.
The indirect effect mediated through poor sleep quality was 0.265 (95% CI: 0.028–0.587, P = .026).
This indirect effect accounted for 12.29% of the total effect of cancer on depression.
Mediation analysis was conducted using nonparametric bootstrap with 5000 resamples.
Sleep quality was proxied by a single item capturing one dimension of sleep disturbance.
The direct effect of cancer on depression remained significant at 1.892 (95% CI: 0.246–3.538, P = .024), indicating partial mediation.
Results
Social participation diversity moderated the association between sleep quality and depression.
The sleep quality × social participation interaction term was statistically significant (β = -0.134, SE = 0.043, P = .002).
The negative interaction coefficient indicates that greater social participation diversity attenuated the path from poor sleep to depression.
Social participation diversity was constructed from 6 types of activities and summarized as a variety index.
Moderation was tested via linear models incorporating the sleep quality × social participation interaction term.
Methods
The study used a cross-sectional design with several methodological limitations that constrain causal inference.
The cross-sectional design prevents conclusions about temporality or causality.
Sleep quality was measured using a single item, which captures only one dimension of sleep disturbance.
Covariates included age, sex, education, partnership, urban residence, retirement, drinking, smoking, and comorbidities.
The authors state findings 'should be interpreted cautiously with respect to temporality and causality.'
Conclusions
The authors identified interventions addressing sleep problems and supporting social engagement as warranting further evaluation.
The authors call for evaluation in 'longitudinal and interventional studies.'
The mediation pathway through sleep quality suggests sleep may be a potential intervention target in the cancer-depression relationship.
The moderating role of social participation diversity suggests social engagement may buffer the negative effect of poor sleep on depression.
The study population was restricted to adults aged 45 and above in China, limiting generalizability.
What This Means
This research suggests that among Chinese adults aged 45 and older, having cancer is associated with higher levels of depression, and that part of this relationship works through poorer sleep quality. Using data from nearly 17,550 participants in a large national Chinese survey conducted in 2018, researchers found that the total effect of cancer on depression was substantial, and that roughly 12% of this effect could be explained by the fact that cancer is associated with worse sleep, which in turn is associated with more depression. The remaining majority of the cancer-depression link appeared to operate through other pathways not captured in this study.
This research also suggests that the connection between poor sleep and depression is not fixed — it appears to be weaker among people who engage in a greater variety of social activities. People who participated in more diverse types of social activities (out of six measured types) showed a reduced association between poor sleep and depression compared to those with less varied social engagement. This points to social participation as a potential buffer against the mental health consequences of sleep problems in this population.
Because the study was conducted at a single point in time (cross-sectional design) and sleep was measured with only one survey question, the findings cannot establish that cancer caused poor sleep or that poor sleep caused depression — only that these factors are statistically associated in a pattern consistent with that pathway. The authors caution that these results should be interpreted carefully, and that future research using longer-term follow-up studies and more comprehensive sleep measures is needed to confirm these findings and evaluate whether improving sleep or supporting social engagement could help reduce depression in people with cancer.
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Bai Y, Li Z, Li C, Chen Q, Wan Y. (2026). Cancer and depression in middle-aged and elderly Chinese: The mediating role of sleep quality and the moderating role of social participation diversity - Evidence from CHARLS 2018.. Medicine. https://doi.org/10.1097/MD.0000000000048912