Researchers at UC Berkley investigated if broken sleep is bad for cardiovascular health and how it might cause hardening of the arteries.
Cardiovascular disease is one of the leading causes of death in the United States, linked to around 12,000 fatalities each week. It is caused by atherosclerosis, a build-up of fatty plaques inside the arteries (sometimes called “hardening of the arteries”), that can lead to damage of the heart, brain, and other organs. Smoking, obesity, lack of exercise, poor diet, and high blood pressure are known risk factors for cardiovascular disease. Some studies have suggested that poor-quality broken sleep may also be a risk factor. Researchers at UC Berkley, United States, investigated the link between broken sleep and cardiovascular disease and the underlying biological processes that may connect them. They recently reported their findings in PLOS Biology.
Broken sleep linked to increased atherosclerosis risk
The researchers analyzed patient data collected as part of the US Multi-Ethnic Study of Atherosclerosis to produce a statistical model based on more than 1,600 middle-aged and older adults. They looked at the effect of sleep quality on heart health, independent of other cardiovascular risk factors such as age, gender, smoking, and blood pressure. They also tracked study participants, analyzing their blood test results to gauge the build-up of atherosclerotic plaque. Participants’ sleep quality was assessed by using wrist-monitors worn at home for a week and by measuring brain activity during sleep in a night spent at a sleep laboratory.
The analysis showed that disrupted sleep patterns were linked to higher levels of circulating inflammatory white blood cells (monocytes and neutrophils) that are known to be important in the development of atherosclerotic plaque.
Increase in inflammatory cells may be link between broken sleep and atherosclerosis
The study indicates that broken sleep raises circulating levels of inflammatory white blood cells and increases the risk of atherosclerosis and cardiovascular disease. The results are in line with earlier laboratory studies in mice showing that experimentally-induced broken sleep led to increases in inflammatory white blood cells and atherosclerotic plaque formation. “In revealing this link with chronic inflammation, the findings suggest a missing middleman that is brokering the bad deal between fragmented sleep and the hardening of blood vessels,” said study senior author Professor Matthew Walker.
The study also highlights that getting a good night’s sleep could be as important for cardiovascular health as controlling blood pressure, reducing weight, stopping smoking, and getting more exercise. “If you track your sleep patterns using objective measures, the same way you track your weight, blood pressure or cholesterol, you can make modifications to your sleep habits, which could make a tangible difference to later life health outcomes,” commented Vyoma Shah, co-lead author of the study. The sleep experts’ tips to improve sleep quality include maintaining a regular sleep routine and avoiding use of digital devices such as phones an hour before bedtime.
The researchers suggest that broken sleep could also be linked to several other diseases where inflammation is a possible underlying cause, such as major depression and Alzheimer’s disease, and these are areas for future research.
Written by Julie McShane, MA MB BS
Vallat R, Shah VD, Redline S, et al. Broken sleep predicts hardened blood vessels. PLOS Biology, Published online June 4, 2020. https://doi.org/10.1371/journal.pbio.3000726 2.
University of California – Berkley. Press release 5 June 2020. “Fitful nightly sleep linked to chronic inflammation, hardened arteries.” https://www.eurekalert.org/pub_releases/2020-06/uoc–fns060520.php
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