Sleep irregularity and the association with hypertension and blood pressure levels: the ELSA-Brasil study.

Objective: To evaluate the associations of sleep irregularity with hypertension (HTN) and blood pressure (BP) levels.
Methods: Adult participants from the ELSA-Brasil performed a clinical evaluation including objective sleep duration (actigraphy), insomnia, and a sleep study for defining obstructive sleep apnoea (OSA). To quantify sleep irregularity, we used two parameters obtained through actigraphy: 7-day standard deviation (SD) of sleep duration and 7-day SD of sleep-onset timing. A multivariate analysis was used to determine the independent associations of sleep irregularity with HTN and SBP/DBP values.
Results: We studied 1720 participants (age 49 ± 8 years; 43.4% men) and 27% fulfilled the HTN diagnosis. After adjustments for age, gender, race, BMI, excessive alcohol consumption, physical activity intensity, urinary sodium excretion, insomnia, objective sleep duration and OSA (apnoea-hypopnoea index ≥15 events/h), we found that the continuous analysis of 7-day SD of sleep duration was modestly associated with prevalent HTN. However, 7-day SD of sleep duration more than 90 min was independently associated with SBP [ β : 1.55; 95% confidence interval (CI) 0.23-2.88] and DBP ( β : 1.07; 95% CI 0.12-2.01). Stratification analysis excluding participants with OSA revealed that a 7-day SD of sleep duration greater than 90 min was associated with a 48% higher chance of having HTN (OR: 1.48; 95% CI: 1.05-2.07). No significant associations were observed for the SD of sleep-onset timing.
Conclusion: Objective measurement of sleep irregularity, evaluated by SD of sleep duration for 1 week, was associated with HTN and higher BP levels, especially in participants without OSA.
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