Association of psychological symptoms with poor sleep quality in adults: a cross-sectional network analysis and effect modification by thyroid hormones.
Xie M, Liu Q, et al. • Frontiers in endocrinology • 2026
Elevated psychological symptom severity was positively associated with poor sleep quality prevalence, and this association appeared to be modified by FT3 levels, with depressive symptoms and subjective sleep quality emerging as central nodes and daytime dysfunction and FT3 serving as key bridge nodes across psychological, sleep, and thyroid domains.
Key Findings
Results
Participants in the highest quartile of Global Severity Index (GSI) scores had a 5.81-fold increased prevalence of poor sleep quality compared to those in the lowest quartile.
Modified Poisson regression with robust sandwich variance estimators (HC3) was used to estimate prevalence ratios (PRs)
PR = 5.81, 95% CI: 4.86–6.95, P < 0.001 after adjusting for potential confounders
GSI scores were derived from the Symptom Checklist-90 (SCL-90)
Poor sleep quality (PSQ) was defined based on Pittsburgh Sleep Quality Index (PSQI) scores
Study enrolled 3,694 adults undergoing routine health screening at Sichuan Provincial People's Hospital between April 2022 and December 2025
Results
Free triiodothyronine (FT3) significantly modified the association between psychological symptoms and poor sleep quality.
PR for interaction per 1-unit GSI increase = 1.35, 95% CI: 1.24–1.46, P < 0.001
In the below-median FT3 group, the prevalence ratio was 1.61 (95% CI: 1.53–1.69)
In the above-median FT3 group, the prevalence ratio increased to 2.26 (95% CI: 2.02–2.53)
Effect modification was tested using multiplicative interaction terms in stratified and continuous-variable models
Results
The modifying effects of TSH and FT4 on the psychological symptoms–poor sleep quality association were not statistically significant in continuous models.
Both thyroid-stimulating hormone (TSH) and free thyroxine (FT4) were tested for effect modification using multiplicative interaction terms
Neither TSH nor FT4 reached statistical significance in continuous-variable models
This contrasts with the significant modification observed for FT3
Results
Depressive symptoms, anxiety, and subjective sleep quality were among the nodes with the highest expected influence in the mixed psychological-sleep-thyroid symptom network.
A mixed 'psychological-sleep-thyroid' symptom network was constructed to calculate expected influence and bridge strength of nodes
Expected influence measures a node's overall impact within the network
Depressive symptoms and subjective sleep quality emerged as central nodes in the network
Results
Daytime dysfunction and FT3 demonstrated substantial cross-module bridge expected influence in the symptom network.
Bridge expected influence measures a node's role in connecting different symptom clusters or modules
Daytime dysfunction served as a key bridge node across psychological and sleep domains
FT3 served as a key bridge node connecting the thyroid domain with the psychological and sleep domains
The network analysis characterized the mixed psychological-sleep-thyroid symptom structure
Methods
The study population consisted of 3,694 adults undergoing routine health examinations classified into poor sleep quality and normal control groups.
Participants were recruited from the Health Management Center of Sichuan Provincial People's Hospital
Recruitment period spanned April 2022 to December 2025
Classification into PSQ versus normal control groups was based on PSQI scores
Psychological symptoms were measured using the Symptom Checklist-90 (SCL-90)
This was a cross-sectional study design
What This Means
This research suggests that people with more severe psychological symptoms — such as depression and anxiety — are substantially more likely to have poor sleep quality. Among over 3,600 adults who came in for routine health check-ups in China, those with the highest levels of psychological distress were nearly six times more likely to report poor sleep compared to those with the lowest levels. The study also found that a thyroid hormone called free triiodothyronine (FT3) appeared to amplify the relationship between psychological distress and sleep problems — people with higher FT3 levels showed a stronger link between psychological symptoms and poor sleep than those with lower FT3 levels. Importantly, the other thyroid hormones measured (TSH and FT4) did not show this same modifying effect.
The researchers also mapped out a 'network' showing how different symptoms — psychological, sleep-related, and thyroid — connect to and influence one another. In this network, depressive symptoms and subjective sleep quality were identified as the most 'central' nodes, meaning they had the greatest overall influence on other symptoms in the network. Daytime dysfunction (problems functioning during the day due to poor sleep) and FT3 acted as 'bridge' nodes, linking the psychological and sleep symptom clusters to the thyroid cluster.
This research suggests that the relationship between mental health and sleep is not isolated — thyroid hormone levels, particularly FT3, may play a meaningful role in shaping how strongly psychological distress translates into sleep problems. Because this was a cross-sectional study (a snapshot in time), it cannot determine which came first or establish cause and effect. The authors note that future longitudinal studies are needed to understand the sequence of these relationships and to explore whether interventions targeting FT3-related pathways or daytime functioning could help reduce sleep disturbances in people with psychological symptoms.
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Xie M, Liu Q, Yang R, He J, Luo Z, Xiong H, et al.. (2026). Association of psychological symptoms with poor sleep quality in adults: a cross-sectional network analysis and effect modification by thyroid hormones.. Frontiers in endocrinology. https://doi.org/10.3389/fendo.2026.1926090