Sleep quality modifies diet–blood pressure association in older adults

Sleep quality modified the association between dietary pattern and systolic blood pressure in a cross-sectional study of 201 middle-aged and older adults living in a community in Shijiazhuang, Hebei Province. The study, published as research in BMC Public Health, found that the relationship between Mediterranean Diet Score and systolic blood pressure differed according to sleep quality: the inverse association was strongest among participants with better sleep and was attenuated as sleep quality worsened. Researchers used survey data collected in 2023 from adults aged 45 years and above, describing the results as hypothesis-generating because the sample was modest and the design did not track participants over time.

Participants’ diets were assessed with the Mediterranean Diet Score, abbreviated MDS, and sleep quality was evaluated with the Pittsburgh Sleep Quality Index, or PSQI. Lower PSQI scores indicated better sleep quality, whereas higher scores indicated poorer sleep. The researchers applied a moderation model to examine whether the diet–blood pressure association varied across levels of sleep quality, while controlling for several covariates. The central adjusted interaction between MDS and PSQI was significantly associated with systolic blood pressure, with a regression coefficient of 1.112, a test statistic of 2.339 and a P value below 0.05. This statistical interaction supported the study’s main result: the estimated diet–blood pressure association was not identical across the measured sleep-quality levels.

Simple-slope analyses provided more detail about that variation. Among participants with lower PSQI scores, indicating better sleep quality, higher MDS values were associated with lower systolic blood pressure. The estimated coefficient was −3.255, but this association did not reach statistical significance, with P = 0.148 and a reported 95% confidence interval of −7.673 to −1.162. At the mean PSQI level, the estimated association between MDS and systolic blood pressure was close to zero and non-significant: β = −0.046, P = 0.978, with a 95% confidence interval of −3.381 to 3.289. For participants with higher PSQI scores, indicating poorer sleep quality, the estimate shifted to a positive direction, β = 3.164, but it was also non-significant, with P = 0.136 and a 95% confidence interval of −1.006 to 7.334. Thus, the individual simple-slope estimates did not meet the study’s statistical-significance threshold, even though the overall interaction term did.

Across the analysis, the pattern was consistent with a healthier dietary pattern being associated with lower systolic blood pressure and with that inverse association weakening as PSQI scores increased. The authors reported that the MDS-by-PSQI interaction remained significant after adjustment for multiple covariates and was consistent when PSQI was analyzed either continuously or after being divided into two categories. The findings therefore identify sleep quality as a contextual factor in the observed association between diet and blood pressure, rather than demonstrating that changing sleep or diet would cause blood pressure to fall. The cross-sectional survey measured diet, sleep and blood pressure without establishing their temporal sequence, and the authors noted that larger longitudinal and intervention studies would be needed to confirm the results. No clinical recommendation or causal conclusion follows directly from the analysis.

Subject of Research: How sleep quality modifies the association between Mediterranean Diet Score and systolic blood pressure in middle-aged and older adults

Article Title: Sleep quality moderates the association between diet and blood pressure in middle-aged and older adults: a cross-sectional study

Article References: Wu, R., Shi, B., Kang, H., Yang, Y., Yang, R., Liang, Z., Chen, W., & Chen, F. (2026). Sleep quality moderates the association between diet and blood pressure in middle-aged and older adults: a cross-sectional study. BMC Public Health. https://doi.org/10.1186/s12889-026-29721-y

Image Credits: AI Generated

DOI: 10.1186/s12889-026-29721-y

Keywords: sleep quality, systolic blood pressure, Mediterranean Diet Score, Pittsburgh Sleep Quality Index, middle-aged adults, older adults, cross-sectional study, moderation analysis, Shijiazhuang, Sleep, quality, moderates