Adults with sleep disorders had higher odds of rheumatoid arthritis compared with those without sleep disturbances, according to a cross-sectional analysis of data from the National Health and Nutrition Examination Survey published in Arthritis Research & Therapy.
Researchers analyzed data from 28,040 US adults who participated in the 2005 to 2018 National Health and Nutrition Examination Survey cycles. Sleep disorders were identified using a sleep-related item from the Patient Health Questionnaire-9, with patients classified as having sleep disorders if they reported trouble falling asleep, staying asleep, or sleeping too much for more than half the days during a 2-week period. Rheumatoid arthritis status was determined based on self-reported physician diagnosis.
Among participants, 14% were identified as having sleep disorders, and 4% reported having rheumatoid arthritis. The mean age of the study population was 46 years, the mean body mass index was 29 kg/m², and 51% of participants were female.
In weighted multivariate logistic regression analyses, sleep disorders remained associated with higher rheumatoid arthritis prevalence across all adjustment levels. Following adjustment for demographic factors including age, sex, race and ethnicity, body mass index, poverty income ratio, marital status, and education level, the association remained statistically significant. In the fully adjusted model, which additionally accounted for smoking status, hypertension, diabetes, and hyperlipidemia, patients with sleep disorders had 1.76 times the odds of rheumatoid arthritis compared with those without sleep disturbances.
Stratified analyses showed that the association between sleep disorders and rheumatoid arthritis persisted across all examined subgroups, including age (younger than 45 years vs aged 45 years and older), sex, race and ethnicity, body mass index categories, poverty income ratio, education level, smoking status, and the presence of hypertension, diabetes, or hyperlipidemia. No statistically significant interactions were observed.
Sensitivity analyses limited to participants from the 2005 to 2012 National Health and Nutrition Examination Survey cycles yielded consistent findings, supporting the robustness of the results.
Several biological mechanisms may plausibly explain the observed association. Sleep disturbances have been linked to systemic inflammation, altered cytokine activity, and impaired immune regulation, which may contribute to rheumatoid arthritis pathogenesis. Poor sleep quality has also been associated with oxidative stress and neuroendocrine dysregulation that may influence inflammatory pathways relevant to the disease.
The researchers noted several limitations. The cross-sectional study design precluded causal inference or determination of temporal direction. Both sleep disorders and rheumatoid arthritis were assessed through self-report, raising the potential for recall bias and misclassification. The definition of sleep disorders relied on a single question addressing sleep problems over a 2-week period, which may capture transient disturbances rather than clinically diagnosed sleep conditions such as insomnia or sleep apnea. Additionally, the analysis did not account for physical activity, diet, inflammatory biomarkers, or use of sleep or analgesic medications. Participants with missing data on key variables were excluded, which may have introduced selection bias.
“To the best of our knowledge, this is the first nationally representative, population-based study to explore the association between sleep disorders and rheumatoid arthritis in US adults using National Health and Nutrition Examination Survey data,” the researchers wrote. “Our findings indicate a statistically significant association between sleep disorders and the prevalence of rheumatoid arthritis in US adults. However, given the limitations of the cross-sectional design, causal inferences cannot be made.”
The researchers reported no competing interests.
Source: Arthritis Research & Therapy