Associations between vasodilatory capacity, physical activity and sleep among younger and older adults

Exercise promotes cardiovascular health through its direct impact on the vascular endothelium. Conversely, poor sleep quality is associated with endothelial dysfunction, which may explain the increased cardiovascular disease amongst poor sleepers. Yet, the influence of physical activity and poor sleep quality on vascular health is not clear. This study examined the relationships between forearm vasodilatory capacity, self-reported sleep quality and free-living, actigraphy-derived energy expenditure in a group of young and older community dwelling adults. Venous occlusion plethysmography determined baseline and peak forearm blood flow following reactive hyperemia. Sleep quality was measured using the Pittsburgh Sleep Quality Index (PSQI). Measures of body composition were assessed using dual energy X-ray absorptiometry. A total of 104 (61 young; 43 old) participants completed the study. In general, younger participants were more active, as determined by steps per day and average daily energy expenditure, but reported poorer sleep quality. In the combined sample, those who reported moderate sleep disturbances (PSQI total score; 11-15) had significantly lower vasodilatory capacity (16.8 +/- A 7.6 ml/100 ml/min) compared to those who reported no sleep disturbance (PSQI total score; 0-5) (22.3 +/- A 7.2 ml/100 ml/min) or mild sleep disturbance (PSQI total score; 6-10) (22.3 +/- A 8.1 ml/100 ml/min) (p < 0.01). After adjustment for physical activity, total body fat and age, moderately poor sleep remained an independent predictor of forearm vasodilatory capacity. These findings suggest that any positive vascular benefits accrued through increased physical activity might be offset by the negative consequences of chronically disturbed sleep.