Effect of five nights of sleep extension on peripheral vascular function: a randomized crossover investigation into long sleep duration

Long sleep duration, defined as ≥9 hours, is associated with increased cardiovascular mortality. We sought to determine the effect of sleep extension on markers of peripheral vascular health. Twelve middle-aged adults (45 ± 5y) were randomly assigned to spend five nights with 8 hours (control) or 10+ hours time in bed (TIB) in a crossover fashion while sleep was assessed using wrist actigraphy. Peak reactive hyperemia in the forearm was measured using venous-occlusion plethysmography as an index of microvascular vasodilation. Nighttime and morning blood pressure was recorded along with carotid-femoral pulse wave velocity (index of arterial stiffness). Average sleep duration was 7.1 ± 0.3 and 9.3 ± 0.3 hours for 8 and 10+ hours TIB (<i>P</i> < 0.001), respectfully. On average, sleep was extended by 127 ± 29 minutes with nine participants reaching average sleep durations >9 hours. Extended sleep did not change nighttime or morning blood pressure, or pulse wave velocity (all <i>P</i> > 0.05). In contrast, peak forearm vascular conductance (FVC, 0.27 ± 0.08 vs. 0.23 ± 0.07 ml/100ml/min/mmHg, <i>P </i>= 0.02) and total excess flow (28 ± 9 vs. 24 ± 11 ml/100ml, <i>P </i>< 0.01) were increased following sleep extension. The change in FVC and total excess flow were inversely correlated with the change in wake after sleep onset and change in TIB (both r = -0.62, <i>P </i>< 0.05), respectively, but not with sleep duration. These results demonstrate that extended time in bed accompanied by long sleep durations does not impair peripheral vascular function, but rather, may increase microvasculature vasodilatory capacity in midlife adults.