['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.', '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.', 'Sleep-wake mean arterial pressure (MAP) ratios.', '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.'] Are low life purpose and high hostility related to an attenuated decline in nocturnal blood pressure?