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Introduction: Nocturnal blood pressure (BP) dipping determined from 24-hour ambulatory blood pressure monitoring (ABPM) is associated with reduced cardiovascular disease (CVD) risk. Physical activity lowers the risk of CVD related, in part, to preserved endothelial function and lower aortic stiffness, however the relation between physical activity and nocturnal dipping remains unclear. The objective of our cross-sectional retrospective analysis was to assess the relation between physical activity and nocturnal BP dipping, and whether this relation was confounded by measures of vascular function. We hypothesized that higher levels of physical activity would be associated with greater nocturnal BP dipping. Methods: Healthy adults (n=172, age 19 to 65 years, 55% female) had 24-hour ABPM measured. BP recordings were taken every 30 min during the daytime and every 60 min during the nighttime. Nocturnal “dippers” had a 10-20% difference between their mean daytime and nighttime systolic BP and “non-dippers/inverse dippers” had <10% difference. The modifiable activity questionnaire was used to assess physical activity levels via self-reported days/week with greater than 30 min of moderate activity (3.0-6.0 METs) and vigorous activity (>6.0 METs). Endothelial function (brachial artery flow-mediated dilation, FMD), and aortic stiffness (carotid-femoral pulse wave velocity, cfPWV) were also assessed. Results: Nocturnal BP dippers performed more days/week of moderate and vigorous physical activity compared to non-dippers (P=0.007 and P=0.008, respectively). Both moderate (B=0.386, P=0.042) and vigorous physical activity (B=0.604, P=0.002) were associated with nocturnal BP dipping in univariate linear regression analyses. However, only vigorous activity (B=0.926, P=0.001) remained associated with nocturnal BP dipping after adjustment for age, BMI, 24-hr systolic BP and diastolic BP, brachial FMD and cfPWV. Conclusion: Vigorous physical activity may attenuate CVD risk in part from enhanced nocturnal BP dipping. Future studies should investigate additional mechanisms by which vigorous physical activity may enhance nocturnal BP dipping. This study was supported by grants from the National Institutes of Health (AG063790; HL014388, HL07121; AG043722). Dr. Pierce is supported by the Russell B. Day and Florence D. Day Endowed Chair in Liberal Arts and Sciences, University of Iowa. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.