Adequate sunlight exposure and good sleep quality are associated with reduced odds of mental-physical multimorbidity in community-dwelling older adults.
Key Findings
Results
Approximately half of the 1,018 participants had two or more chronic conditions (multimorbidity), distributed across physical-only, mental-only, and mental-physical categories.
Total sample size was 1,018 participants with a mean age of 68.56 years; 48.53% were female.
Physical-only multimorbidity prevalence was 21.22%.
Mental-only multimorbidity prevalence was 1.57%.
Mental-physical multimorbidity prevalence was 28.49%.
Study was cross-sectional and conducted in two representative areas in Northwest China.
Results
Sunlight exposure was significantly inversely associated with mental-physical multimorbidity in older adults.
Adjusted odds ratios (AORs) for sunlight exposure were significantly lower in older adults with mental-physical multimorbidity compared with those without.
The association between sunlight exposure and multimorbidity was not statistically significant for physical-only or mental-only multimorbidity categories.
Sunlight exposure data were collected via self-reported questionnaires.
Stratified analyses showed the inverse association between sunlight exposure and multimorbidity was present only in males, not females.
Results
Poor sleep quality, insomnia, snoring, and daytime sleepiness were associated with higher odds of multimorbidity across multiple categories.
Higher odds for poor sleep quality, insomnia, snoring, and daytime sleepiness were observed in older adults with either category of multimorbidity.
Sleep parameters were collected using self-reported questionnaires covering core sleep parameters and sleep-related symptoms.
These associations were examined using separate multivariable binary logistic regression analyses.
Results
Adequate sleep duration, non-extreme sleep timing, and higher sleep efficiency were associated with reduced odds of overall and mental-physical multimorbidity.
Sleep duration, non-extreme sleep timing, and sleep efficiency were each associated with reduced odds for overall multimorbidity.
These same sleep parameters were associated with reduced odds specifically for mental-physical multimorbidity.
Associations were derived from multivariable binary logistic regression analyses adjusted for potential confounders.
Results
Sex and age stratified analyses revealed differential associations between sleep, sunlight exposure, and multimorbidity.
Associations between sleep and multimorbidity were stronger in females than in males.
Associations between sleep and multimorbidity were stronger in the younger-old age group compared to older age groups.
Sunlight exposure was inversely associated with multimorbidity only in males, with no significant association observed in females.
These findings emerged from pre-specified stratified analyses within the cross-sectional study design.
Methods
The study classified multimorbidity into three distinct clusters to differentiate the role of mental illness in co-occurring chronic conditions.
Multimorbidity was clustered into physical-only, mental-only, and mental-physical categories.
This categorization allowed separate examination of associations between lifestyle factors and multimorbidity with and without mental illness.
Separate multivariable binary logistic regression analyses were performed for each multimorbidity category.
The study population consisted of community-dwelling older adults, limiting generalizability to institutionalized populations.
What This Means
This research suggests that among older adults living in the community in Northwest China, having multiple chronic diseases at the same time (called multimorbidity) is very common — about half of the roughly 1,000 participants studied had two or more chronic conditions. The researchers found that conditions involving both physical and mental health together were particularly common (about 28% of participants), and that getting enough sunlight and sleeping well were both linked to lower chances of having this combined physical-mental type of multimorbidity. Poor sleep in various forms — including bad sleep quality, insomnia, snoring, and daytime sleepiness — was associated with higher odds of having multiple chronic diseases across several categories.
The study also found that not all older adults were affected equally. Sleep problems were more strongly linked to multimorbidity in women and in the younger segment of the older adult population, while the protective association of sunlight exposure with multimorbidity was only seen in men. Sleeping for an appropriate duration, going to sleep and waking at non-extreme times, and having efficient sleep (actually sleeping during time in bed) were all linked to reduced odds of multimorbidity.
This research suggests that lifestyle factors like sunlight exposure and sleep habits may be meaningfully connected to the burden of multiple chronic diseases in older adults, particularly when mental health conditions are part of the picture. Because this was a cross-sectional study — meaning it captured a snapshot in time rather than following people over years — it cannot establish whether poor sleep or low sunlight exposure cause multimorbidity or vice versa. Nonetheless, these findings highlight the potential importance of monitoring and supporting healthy sleep and outdoor light exposure as part of broader health strategies for aging populations.
Zhang N, Gao J, Che Y, Wang C, Chen S, Yu S, et al.. (2026). Association between sleep, sunlight exposure, and multimorbidity in older adults with and without mental illness.. Frontiers in public health. https://doi.org/10.3389/fpubh.2026.1751563