Older adults with irregular sleep habits may face a higher risk for hardened arteries than their peers with regular bedtimes and hours of sleep, new research suggests.
The study, published Wednesday in the Journal of the American Heart Association, found adults 45 and older who fell asleep at different times each night and slept an inconsistent number of hours were more likely to develop atherosclerosis, a buildup of plaque in artery walls that can lead to a heart attack or stroke.
"Maintaining regular sleep schedules and decreasing variability in sleep is an easily adjustable lifestyle behavior that can not only help improve sleep, but also help reduce cardiovascular risk for aging adults," lead study author Kelsie Full said in a news release. Full is an assistant professor of medicine in the division of epidemiology at Vanderbilt University Medical Center in Nashville, Tennessee.
Prior research has linked poor sleep habits – including getting too little, too much or fragmented sleep – with heart disease, obesity, Type 2 diabetes, high blood pressure and other cardiovascular disease conditions. The American Heart Association recommends adults get seven to nine hours of sleep each night. The AHA recently added sleep to Life's Essential 8, its list of recommended behaviors and factors for optimizing heart and brain health.
In the new study, researchers analyzed the sleep habits of more than 2,000 men and women, with an average age of 69, who were enrolled in the Multi-Ethnic Study of Atherosclerosis between 2010 and 2013. Participants, who were from six U.S. communities, were free of cardiovascular disease when the sleep ancillary study began.
The participants wore wrist devices that detected when they were awake and when they were sleeping. They also completed a sleep diary for seven consecutive days and a one-night, in-home sleep study that tracked breathing, sleep stages, heart rate and sleep interruptions.
Sleep duration was measured by the total amount of time spent in bed fully asleep. Researchers also tracked the time participants fell asleep each night.
How much atherosclerosis a person developed was measured in several ways. Researchers analyzed calcified fatty plaque buildup in the arteries (coronary artery calcium), fatty plaque buildup in neck arteries (carotid plaque), thickness of the inner two layers of the neck arteries (carotid intima-media thickness) and narrowed peripheral arteries (the ankle-brachial index).
Compared to participants with consistent sleep duration, those whose sleep duration varied by more than two hours within the same week were 1.4 times more likely to have high levels of coronary artery calcium, a major contributor to cardiovascular events such as heart attacks and strokes. They also were 1.12 times more likely to have carotid plaque and nearly two times more likely to have abnormal results from an ankle-brachial index, which compares blood pressure at the ankle and in the arm to test for atherosclerosis and stiffness in the blood vessels.
Participants whose bedtimes varied by more than 90 minutes within the same week were 1.43 times more likely to have high coronary artery calcium, compared to those whose bedtimes varied by 30 minutes or less.
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