METHODS: 602 adults (age mean(SD) =56.96(5.51) years, female=60%) from the Raine Study who were not evening or night shift workers were assessed for OSA (in-laboratory polysomnography; apnea hypopnea index (AHI) ≥15events/hour), hypertension (doctor diagnosed; or systolic blood pressure ≥140mmHg and/or diastolic ≥90mmHg) and sleep (wrist actigraphy for ≥5 days). A sleep regularity index (SRI) was determined from actigraphy. Participants were categorised by tertiles as severely irregular, mildly irregular, or regular sleepers. Logistic regression models examined the interrelationships between SRI, OSA and hypertension. Covariates included age, sex, body mass index, actigraphy sleep duration, insomnia, depression, activity, alcohol, smoking, and anti-hypertensive medication.

RESULTS: Compared to regular sleepers, participants with mildly irregular (OR 1.97, 95% CI 1.20-3.27) and severely irregular (OR 2.06, 95% CI 1.25-3.42) sleep had greater odds of OSA. Compared to those with no OSA and regular sleep, OSA and severely irregular sleep combined had the highest odds of hypertension (OR 2.34 95% CI 1.07-5.12; p for interaction=0.02) while those with OSA and regular/mildly irregular sleep were not at increased risk (p for interaction=0.20).