Poor sleep efficiency, longer wake up associated with increased CVD risk
Individuals with poorer sleep efficiency and longer time spent awake from sleep onset to final awakening had increased risk for incident CVD, according to results published in the Journal of the American Heart Association.
“Several studies have showed that sleep efficiency is closely related to cardiovascular risk factors,” Bin Yan, MD, research assistant in the department of clinical research center and the department of psychiatry at the First Affiliated Hospital of Xi’an Jiaotong University in Xi’an, China, and colleagues wrote. “However, there is little evidence to support an association between objective sleep efficiency and major CVD based on polysomnography.”
Researchers evaluated 3,810 participants (mean age, 63 years) from the Sleep Heart Health Study, a decade-long community-based study, to investigate associations between CVD and objectively measured sleep efficiency. CVD was assessed in each participant during the follow-up period. Sleep efficiency was measured by in-home polysomnography records and included sleep efficiency and wake up after sleep onset.
The primary outcome was major adverse CV events, defined as CVD mortality, congestive HF, MI and stroke. The key secondary outcome was major adverse CV events plus revascularization.
Participants were stratified by sleep efficiency as follows: 90% or more, 85% to 89.9%, 80% to 84.5% or less than 80%.
After a mean follow-up period of 10.9 years, the primary outcome occurred in 12.4% of participants and the secondary outcome occurred in 22% of the cohort.
Participants with poor sleep efficiency (< 80%) had higher incidence of the primary outcome (17.5%) and the key secondary outcome (32.3%) compared with those with 85% to 89.9% sleep efficiency (13.2% and 23.3%, respectively), those with 80% to 84.9% sleep efficiency (10.5% and 19.8%, respectively) and those with 90% or better sleep efficiency (7.3% and 14.6%, respectively; P for trend for both < .001).
Researchers observed significant associations between poor sleep efficiency and the primary outcome (HR = 1.338; 95% CI, 1.025-1.745; P = .032) and the secondary outcome (HR = 1.25; 95% CI, 1.027-1.521; P = .026) following multivariate regression analysis. Poor sleep efficiency also predicted CVD mortality (HR = 1.887; 95% CI, 1.224-2.909; P = .004).
There was also a close correlation with wake up after sleep onset (> 78 minutes) and the primary outcome (HR = 1.436; 95% CI, 1.066-1.934; P = .017), the key secondary outcome (HR = 1.374; 95% CI, 1.103-1.712; P = .005) and CVD mortality (HR = 2.24; 95% CI, 1.377-3.642; P = .001).
According to the researchers, these results suggest improving sleep efficiency may reduce CVD risk because reduced sleep efficiency during the night along with sleep environment, sleeping habit, daytime nap habit and caffeine or alcohol intake also influenced sleep efficiency in various chronic diseases.
“Our results showed that low sleep efficiency and long wake after sleep onset were prone to have a high proportion of incident CVD,” the researchers wrote. “This indicates that sleep efficiency and wake after sleep onset may predict the incidence of CVD.”