Objective: An attenuation of the nighttime decline in blood pressure (BP) predicts cardiovascular disease and cardiovascular-related mortality, beyond daytime BP levels. We investigated whether positive and negative psychological attributes were associated with sleep wake BP ratios and examined sleep parameters as potential mediators of these relationships. Design: Two hundred twenty-four participants (50% men; 43% Black; mean age = 60 years) underwent ambulatory BP monitoring for 2 days and nights. Self-reports of positive and negative psychological attributes were collected. In-home polysomnography was conducted for 2 nights, and a wrist actigraph was worn for 9 nights. Main Outcome Measures: Sleep wake mean arterial pressure (MAP) ratios. Results: After adjustment for demographics, body mass index, and hypertensive status, low life purpose and high hostility were associated with high sleep wake MAP ratios. Depression, anxiety, and optimism were not related to MAP ratios. Sleep latency, fragmentation, architecture, and the apnea hypopnea index were examined as potential mediators between psychological attributes and MAP ratios; only long sleep latency mediated the relationship between hostility and MAP ratios. Conclusion: Low life purpose and high hostility are associated with high sleep wake BP ratios in Black and White adults, and these relationships are largely independent of sleep.