Snoring is Related to the Elevation of Morning Blood Pressure

Consequences of snoring independent of obstructive sleep apnea remains controversial. We hypothesized that snoring sound intensity, as assessed by mean tracheal sound energy (Leq) during sleep, is related to morning blood pressure. Subjects were 191 government workers. Overnight tracheal sound recording at home was performed using an IC-recorder. The data were analyzed using a PC-based compressed sound spectrograph system, which yielded the respiratory disturbance index (RDI) and the equivalent tracheal sound pressure level (Leq). Blood pressure was measured in the morning following the overnight monitoring. We stratified the subjects into four groups: lean or normal-weight nonapneics (LNA; RDI < 5/h, BMI < 25, n = 110), overweight nonapneics (ONA; RDI < 5/h, BMI < 25, n = 20), lean or normal-weight apneics (LA; RDI < 5/h, BMI < 25, n = 27), and overweight apneics (OA; RDI < 15/h, BMI < 25, n = 16). Pearson’s correlation analysis and multiple regression analysis were employed to elucidate the association between snoring and morning blood pressure. Both systolic and diastolic blood pressure values (SBP and DBP) in the morning in LNA were lower than those in ONA, LA and OA (116/73 vs. 127/80, 128/82, 133/84 mmHg). Leq was correlated to both SBP and DBP in the morning (r = 0.38, p < 0.0001; r = 0.33, p = 0.0004, respectively) only in LNA, not in other groups. In LNA, multiple regression analysis showed that Leq was significantly associated with morning SBP after adjustment for the RDI, BMI and other confounding factors (p = 0.022), but not with morning DBP. Snoring is independently related to the elevation of morning blood pressure in lean or normal-weight workers. The authors thank Kenji Hirayama for useful suggestion.