Effects of obstructive sleep apnea on nocturnal changes in blood pressure - a retrospective study

To explore the effects of obstructive sleep apnea (OSA) on nocturnal changes in blood pressure (BP), we enrolled 2037 participants who underwent polysomnography (PSG) between 2019 and 2020 and examined BP changes before and after sleep. BP was measured in the evening and the following morning using an electronic wrist sphygmomanometer in the supine position. The severity of OSA was determined by PSG and graded based on the apnea/hypopnea index (AHI). Participants with OSA (AHI ≥ 5 events/h) had significantly higher morning systolic BP (SBP) and diastolic BP (DBP) compared to their evening measurements. BP values, whether measured in the evening or the morning, as well as the nocturnal changes (differences between morning and evening values), showed significant correlations with the AHI for both SBP and DBP, even after adjusting for confounders such as age, sex, body mass index, and the presence of comorbidities, including hypertension, heart failure, coronary artery disease, diabetes, renal disorder, and cerebrovascular attack. After standardization, the extent of nocturnal changes in DBP was greater than SBP, especially among participants with severe OSA. In a logistic regression model with serial multivariate adjustments, OSA was found to be independently associated with morning hypertension, particularly in individuals with moderate to severe OSA.