COMPARISONS OF OBSTRUCTIVE SLEEP APNEA AND CARDIOVASCULAR HEALTH INDICES AMONGST CHRONOTYPES

Chronotype is characterized by individual preferences in the timing of sleep and activity across a 24-h cycle. Health differences between chronotypes have been identified but are not fully understood. PURPOSE: To investigate differences in the presence and severity of obstructive sleep apnea (OSA) and cardiovascular health indices amongst morning, evening, and intermediate chronotypes. METHODS: This study is part of a larger, on-going investigation. Preliminary analyses include a subsample of 98 adults (52% women, 60% white) from the Southeastern US who underwent a series of assessments (e.g., height, body mass, and noninvasive measures of central systolic and diastolic blood pressure [cSBP and cDBP]) all performed in the morning following an overnight fast. The Circadian Energy Scale (CIRENS; -4 to +4, with higher scores indicating evening chronotype) was used to determine chronotype. Participants also completed a home sleep study to evaluate the presence and severity of OSA, quantified using the apnea hypopnea index (AHI; number of apneas plus hypopneas/h of sleep) and categorized as <5, 5-14.9, 15-29.9, and ≥ 30 events/h of sleep. Analysis of covariance (ANCOVA) was used to explore differences in the presence and severity of OSA and differences in cSBP and cDBP amongst chronotypes. RESULTS: Participants (M ± SD: age = 36 ± 11 y, body mass index [BMI] = 28.5 ± 7.6 kg/m2, cSBP/cDBP = 106.7 ± 13.3/72.6 ± 8.7 mmHg) tended to present with an intermediate chronotype (83.7%) and had AHI severity scores of 9.6 ± 12.6. AHI scores differed significantly between chronotypes (F(1,2) = 5.5; p = 0.005), which remained significant after controlling for age and BMI (F(1,4) = 4.6; p = 0.035). Similarly, cSBP significantly differed between chronotypes (F(1,2) = 3.6; p = 0.033), however these differences were diminished after controlling for age and BMI (F(1,4) = 1.7; p = 0.189). CONCLUSIONS: Differences in OSA severity differed by chronotype, independent of age and BMI, and were highest among individuals with an intermediate chronotype. In contrast, differences in cSBP were attributable to age and BMI and not chronotype per se. Further investigation into chronotype (and associated physiological and behavioral manifestations) is warranted to better understand long-term health implications. Supported by: This work was supported by the National Heart, Lung, & Blood Institute, National Institutes of Health, Bethesda, MD, under Grant [1K01HL145128]; National Institutes of Health Loan Repayment Program, Division of Loan Repayment, National Institutes of Health Bethesda MD, under Grant [L30HL15969].