Sleep-related factors associated with masked hypertension: the Nagahama study.

OBJECTIVES: Masked hypertension, which is characterized by out-of-office hypertension but normal office blood pressure, is a risk factor for cardiovascular disease. However, the factors that contribute to masked hypertension are unclear. We aimed to determine the involvement of sleep-related characteristics in masked hypertension. METHODS: The study included 3844 normotensive (systolic/diastolic blood pressure < 140/90 mmHg) community residents with no antihypertensive drug use at baseline (mean age 54.3 years). Home morning and evening blood pressure, oxygen desaturation during sleep (pulse oximetry), and sleep efficiency (actigraphy) were measured for 1 week. The number of nocturnal urinations during this period was obtained using a sleep diary. RESULTS: Masked hypertension (mean morning and evening blood pressure ≥135/85 mmHg) was detected in 11.7% of study participants, and 79.0% of the participants with masked hypertension had sleep hypertension (≥120/70 mmHg). Multinominal logistic regression analysis identified different factors involved in masked hypertension with and without sleep hypertension; factors for masked hypertension with sleep hypertension included the frequency of at least 3% oxygen desaturation (coefficient = 0.038, P  = 0.001), nocturia (coefficient = 0.607, P  < 0.001), and carotid intima-media thickness (coefficient = 3.592, P  < 0.001). Only carotid intima-media thickness and measurement season were associated with masked hypertension without sleep hypertension. Low sleep efficiency was associated with isolated sleep hypertension but not masked hypertension. CONCLUSION: Sleep-related factors associated with masked hypertension differed depending on the presence of sleep hypertension. Sleep-disordered breathing and nocturnal urination frequency may help identify individuals who need home blood pressure monitoring.