LAUSR

OBJECTIVE Epidemiologic data increasingly supports sleep as a determinant of cardiovascular disease risk. Fewer studies have investigated the mechanisms underlying this relationship using objective sleep assessment approaches. Therefore, the aim of this study was to examine associations between daily blood pressure and both objectively assessed sleep duration and efficiency. METHODS A diverse community sample of 300 men and women ages 21-70, enrolled in the North Texas Heart Study, participated in the study. Actigraphy assessed sleep was monitored over 2 consecutive nights with ambulatory blood pressure sampled randomly within 45-min blocks on the first and second day as well as the second night. RESULTS Overall, sleep duration results paralleled those of sleep efficiency. Individuals with lower sleep efficiency had higher daytime systolic (B=-0.35, SE=0.11, p=.0018, R=0.26) but not diastolic BP (B=-0.043, SE=0.068, p=.52, R=0.17) and higher nighttime BP (systolic: B=-0.37, SE=0.10, p<.001, R=.15; diastolic: B=-0.20, SE=0.059, p<.001, R=.14). Moreover, lower sleep efficiency on one night was associated with higher systolic (B=-0.51, SE=0.11, p<.001, R=0.23) and diastolic BP (B=-0.17, SE=0.065, p=.012, R =.16) the following day. When both sleep duration and efficiency were assessed together, sleep efficiency was associated with daytime systolic BP, while sleep duration was associated with nighttime BP. CONCLUSIONS Lower sleep duration and efficiency are associated with higher daytime systolic BP and higher nighttime BP when assessed separately. When assessed together, sleep duration and efficiency diverge in their associations with BP at different times of day. These results warrant further investigation of these possible pathways to disease.