Women more likely than men to experience CV effects of sleep loss
Sleep loss caused a significant increase in 24-hour and sleep-time BP among healthy young adults, particularly women, according to data published in Hypertension.
Researchers reported that sleep restriction had no effect on any 24-hour BP outcome among men.
“Over the past half century, sleep habits have changed dramatically. Augmented artificial lighting, shift and night work schedules, access to 24-hour services and the recent ubiquitous use of electronic entertainment and communication technology are thought to contribute to shortening habitual sleep duration,” Naima Covassin, PhD, assistant professor of medicine at Mayo Clinic in Rochester, Minnesota, and colleagues wrote. “Currently, 35% of the U.S. adult population (equivalent to 80 million people) report sleeping 6 or less hours.”
To understand the effects of prolonged sleep restriction on 24-hour ambulatory BP, researchers enrolled 20 healthy young participants (mean age, 23 years; nine women) to undergo a 16-day inpatient study. Participants underwent 4 days of acclimation, 9 days of either sleep restriction (4 hours of sleep per night) or control sleep (9 hours of sleep per night) and a 3-day recovery period.
During the trial period, participants consumed a weight-maintenance diet with controlled nutrient composition.
The primary outcome was change in 24-hour BP. Secondary outcomes included various CV biomarkers.
Vascular effects of sleep restriction
Among patients assigned to a restricted sleep schedule, researchers observed a 2.1 mm Hg increase in 24-hour mean arterial pressure compared with the control group (95% CI, 0.6-3.6; P corrected = .016; P for overall condition effect < .001).
A similar trend was observed for 24-hour systolic BP, which increased on average 3.1 mm Hg (95% CI, 0.9-5.3; P corrected = .012) and 24-hour diastolic BP, which increased on average 2.2 mm Hg (95% CI, 0.7-3.7; P corrected = .01; P for overall condition effect for both = .001).
According to a post hoc analysis on sex differences, women in the restricted sleep arm experienced elevated 24-hour mean arterial pressure that averaged 5.2 mm Hg higher (95% CI, 2.8-7.6), 8 mm Hg higher 24-hour systolic BP (95% CI, 5.1-10.8) and 5 mm Hg higher 24-hour diastolic BP (95% CI, 2.4-7.5; P corrected for all < .001) compared with men. Sleep restriction had no effect on any 24-hour BP outcome among men. During the comparable wakefulness, men had lower mean arterial pressure (P = .044) and diastolic BP (P = .04) compared with women, a difference that because more pronounced as the trial progressed.
“Our findings further suggest that sleep debt may be implicated in sex disparities in cardiovascular risk and may be particularly important in understanding the steeper trajectory of BP increases seen in women compared with men,” Covassin and colleagues wrote.
Other CV effects of sleep restriction
In other findings, flow-mediated dilation decreased in response to sleep restriction with a 2.2% reduction by day 13 (95% CI, 3.8 to 0.6; P corrected = .034) and persisted into recovery with a 1.8% reduction still noted by day 16 (95% CI, 3.5 to 0.1; P corrected = .046) compared with the control arm.
Endothelial function was attenuated, and plasma norepinephrine increased during sleep restriction compared with the control group, with significant elevation by day 7 (55.5 pg/mL; 95% CI, 20-91; P corrected = .011) and day 13 (43.9 pg/mL; 95% CI, 8.4-79.4; P = .049).
“Although this analysis was exploratory, these data strongly suggest a potentiated biological vulnerability to sleep deficiency in women, thus providing, for the first time, a deterministic basis for the epidemiological observations of sex-dependent risk of hypertension associated with short sleep,” the researchers wrote. “Our findings are particularly important given recent observations from pooled cohorts challenging conventional knowledge of BP trajectories in men and women by showing that BP increases are steeper in women and the divergence ensues at young ages. Given its widespread prevalence, insufficient sleep may be implicated in such trajectories, compromising the cardioprotection normally exhibited by young women and contributing to their more rapid progression towards hypertension.”