Relationship between snoring sound intensity and daytime blood pressure

We hypothesized that snoring sound intensity may be associated with daytime blood pressure independent of sleep apnea. We aimed to test this hypothesis in a cross-sectional study. The study subjects comprised 515 patients who underwent polysomnography (PSG) for suspected obstructive sleep apnea (OSA) syndrome. Blood pressure was measured in the seated position at rest during the first hospital visit. Snoring sound intensity was assessed by the highest one percentile ambient sound pressure level (L1) while the patient slept during PSG. Of these, 378 patients who had no antihypertensive medication with sufficient data were included in our analysis. We classified the subjects into a non-to-mild OSA group (n = 200; apnea-hypopnea index: AHI < 15) and a moderate-to-severe OSA group (n = 178; AHI >= 15). L1 was correlated with both systolic and diastolic blood pressure (r = 0.30 [P < 0.0001] and r = 0.40 [P < 0.0001], respectively) in all of the subjects. A multivariate regression analysis showed L1 to be significantly associated with both the systolic and diastolic blood pressure after adjusting for AHI and other confounding factors (P = 0.017 and P = 0.012, respectively) only in the non-to-mild OSA group. Snoring sound intensity may be independently associated with daytime blood pressure in patients with either primary snoring or mild OSA.