Sleep as a new 8th measure of cardiovascular health

The study sample consisted of ~2000 middle-aged to older adults from the Multi-Ethnic Study of Atherosclerosis (MESA), an ongoing U.S. study of CVD and CVD risk factors, who participated in a sleep exam and provided comprehensive data on their sleep characteristics.

The research evaluated multiple expanded cardiovascular health scores -- including the American Heart Association's Life's Simple 7 (LS7) metrics -- plus different sleep health measures, to evaluate which sleep parameters should be prioritized for CVD prevention. This study is the first to show that sleep metrics add independent predictive value for CVD events over and above the original 7 CVH metrics.

Importantly, cardiovascular health scores that included sleep duration only as a measure of overall sleep health as well as cardiovascular health scores that included multiple dimensions of sleep health (i.e. sleep duration, efficiency, and regularity, daytime sleepiness, and sleep disorders) were both predictive of future CVD. For the sleep duration metric, sleeping 7 hours or more but less than 9 hours each night was considered indicative of ideal sleep health.

"Our results demonstrate that sleep is an integral component of CVH. In our study, even a CVH score that includes only sleep duration, the most widely measured aspect of sleep health and the most feasible measure to obtain in a clinic or public health setting, predicted CVD incidence," said Nour Makarem, PhD, assistant professor of epidemiology at Columbia Mailman School of Public Health and lead author of the study. "Notably, we also found that a CVH score that incorporated multiple dimensions of sleep health was also significantly associated with incident CVD. Our results highlight the importance of embracing a holistic vision of sleep health that includes sleep behaviors and highly prevalent, mild sleep problems rather than strictly focusing on sleep disorders when assessing an individual's cardiovascular risk."

Overall, the study found that 63 percent of participants slept less than 7 hours per night and 30 percent slept less than 6 hours, while 39 percent and 25 percent had high night-to-night variability in sleep duration and sleep timing, respectively; 14 percent and 36 percent reported having excessive daytime sleepiness and high insomnia symptoms, respectively; and 47 percent had moderate-to-severe sleep apnea (OSA), where breathing repeatedly stops and starts.

According to Nour Makarem and colleagues, the finding that a sleep health score based solely on sleep duration as well as a sleep health score based on multiple sleep dimensions both enhanced the definition of cardiovascular health can be explained, at least in part, by the clustering of sleep problems. The study showed that individuals with a short sleep duration had higher chances of having low sleep efficiency (<85 percent time in bed after lights off spent sleeping), irregular sleep patterns (i.e., variable sleep duration and timing across days), excessive daytime sleepiness, and sleep apnea. Notably, short sleepers also had higher prevalence of overweight/ obesity, type 2 diabetes, and hypertension, suggesting that multiple unhealthy sleep dimensions may occur concurrently and potentially interact, further increasing risk for heart disease.

"Healthcare providers should assess their patients' sleep patterns, discuss sleep-related problems, and educate patients about the importance of prioritizing sleep to promote CVH," noted Makarem. "Furthermore, the formal integration of sleep health into CVH promotion guidance will provide benchmarks for surveillance and ensure that sleep becomes an equal counterpart in public health policy to the attention and resources given to other lifestyle behaviors."

"We recommend that additional research be conducted to examine the expanded definition of CVH that encompasses sleep in relation to lifetime risk of developing CVD. Clinical trials are also needed to evaluate the impact of screening for sleep problems and improving multiple dimensions of sleep health through sleep hygiene interventions on cardiovascular outcomes."

David Goff, MD, PhD, director of the Division of Cardiovascular Sciences at the National Heart, Lung, and Blood Institute (NHLBI), part of the National Institutes of Health (NIH), agreed. "This study provides compelling evidence that sleep metrics are an important factor in cardiovascular health," said Goff, who was not a part of the study team. "Recognizing sleep as an integral part of heart health is a transformative step toward reducing the global burden of cardiovascular disease, the leading cause of death, and reducing health disparities associated with it. We look forward to future research on sleep health that pursues the vision of healthy hearts on a healthy planet."

Co-authors are Marie-Pierre St-Onge and Brooke Aggarwal, Columbia University Irving Medical Center; Susan Redline, Brigham and Women's Hospital and Beth Israel Deaconess Medical Center, Harvard Medical School; Steven Shea, Columbia Mailman School of Public Health and Columbia University Irving Medical Center; Donald Lloyd-Jones and Hongyan Ning, Feinberg School of Medicine, Northwestern University.

The study was supported by National Heart, Lung, and Blood Institute (Grants R00-HL148511, R35 HL135818), National Institute on Minority Health and Health Disparities (Grant P50MD017341-01), American Heart Association (Grant #AHA855050, #AHA811531), National Institutes of Health (Grants R01HL128226 and R01HL142648). MESA is conducted and supported by the National Heart, Lung, and Blood Institute (Grants HHSN268201500003I, N01-HC-95159, N01-HC-95160, N01-HC-95161, N01-HC-95162, N01-HC-95163, N01-HC-95164, N01-HC-95165, N01-HC-95166, N01-HC-95167, N01-HC-95168, N01-HC-95169, UL1-TR-000040, UL1-TR-001079, UL1-TR-001881, and DK06349, and HL098433.)