The association between sleep duration and muscle sympathetic nerve activity

Purpose: Sleep duration is associated with risk of hypertension and cardiovascular diseases. It is thought that shorter sleep increases sympathetic activity. However, most studies are based on acute experimental sleep deprivation that have produced conflicting results. Furthermore, there are limited data available on habitual sleep duration and gold-standard measures of sympathetic activation. Hence, this study aimed to assess the association between habitual sleep duration and muscle sympathetic nerve activity. Methods: Twenty-four participants aged ≥ 18 years were included in the study. Sleep was assessed using at-home 7-day/night actigraphy (ActiGraph™ GT3X-BT) and sleep questionnaires (Pittsburgh Sleep Quality Index and Epworth Sleepiness Scale). Microelectrode recordings of muscle sympathetic nerve activity were obtained from the common peroneal nerve. Participants were categorised into shorter or longer sleep duration groups using a median split of self-report and actigraphy sleep measures. Results: Compared to longer sleepers, shorter sleepers averaged 99 ± 40 min and 82 ± 40 min less sleep per night as assessed by self-report and objective measures, respectively. There were no differences in age (38 ± 18 vs 39 ± 21 years), sex (5 male, 7 female vs 6 male, 6 female), or body mass index (23 ± 3 vs 22 ± 3 kg/m²) between shorter and longer sleepers. Expressed as burst frequency, muscle sympathetic nerve activity was higher in shorter versus longer sleepers for both self-report (39.4 ± 12.9 vs 28.4 ± 8.5 bursts/min, p = 0.019) and objective (37.9 ± 12.4 vs 28.1 ± 8.8 bursts/min, p = 0.036) sleep duration. Conclusions: Shorter sleep duration assessed in a home setting was associated with higher muscle sympathetic nerve activity. Sympathetic overactivity may underlie the association between short sleep and hypertension.