Simple Subjective Sleep Quality and Blood Pressure in Individuals With Optimal Sleep Duration: A Cross-Sectional Study

Background: An individual's simple subjective feeling of having poor sleep quality usually occurs in combination with short sleep duration. Previous studies have mainly investigated the association between simple subjective sleep quality and blood pressure in a general population without considering the complicated issue regarding poor sleep quality and short sleep duration. The aim of this study was therefore to investigate whether poor sleep quality was associated with increased blood pressure in individuals with optimal sleep duration. Methods: A cross-sectional study was conducted on 169 residents aged >= 18 years who lived in a remote island of Okinawa, Japan. The participants had a sleep duration of 6- 7.9 h/day on weekdays and were not taking either sleep medication or antihypertensive medication. Analysis of covariance was used to compare systolic and diastolic blood pressures in the participants grouped according to simple subjective sleep quality. Results: Of the 169 participants, 51 (30.2%) reported that their sleep quality was poor. After adjustment for age, sex, and other potential confounders including sleep duration within optimal levels, the participants aged <= 49 years had mean (95% confidence interval) systolic and diastolic blood pressures (mm Hg) of 121.0 (114.7- 127.3) and 68.7 (63.8- 73.6) in the good sleep quality group, and 127.8 (120.7- 134.9) and 71.8 (66.2- 77.3) in the poor sleep quality group (P = 0.01 and P = 0.14, respectively). However, in those aged >= 50 years, the corresponding means were 130.6 (121.3- 139.8) and 79.1 (73.5- 84.7) in the good-quality group and 126.9 (114.6- 139.2) and 78.0 (70.5- 85.4) in the poor-quality group (P = 0.43 and P = 0.68, respectively). There was a statistically significant interaction between simple subjective sleep quality and age for systolic blood pressure (P value for interaction = 0.04). Conclusions: This study showed that an individual's simple subjective feeling of poor sleep quality was associated with increased systolic blood pressure in participants aged <= 49 years with optimal sleep duration. These findings highlight the importance of easily assessing simple subjective sleep quality in clinical settings even in individuals with optimal sleep duration, in order to prevent and manage hypertension.