Sleeping poorly on a regular basis may lead to the fatty arterial plaque buildup known as atherosclerosis that can result in fatal heart disease.
“We’ve discovered that fragmented sleep is associated with a unique pathway — chronic circulating inflammation throughout the bloodstream — which, in turn, is linked to higher amounts of plaques in coronary arteries,” said study senior author Matthew Walker from the University of California in the US.
For the findings, published in the journal PLOS Biology, the researchers analysed the diagnostic data of more than 1,600 middle-aged and older adults using a national dataset known as the Multi-Ethnic Study of Atherosclerosis.
To isolate the effect of sleep quality on heart health, the study controlled for age, ethnicity, gender, body mass index, sleep disorders, blood pressure and high-risk behaviours such as smoking.
The researchers then tracked the results of the study participants, analysing their blood tests, their calcium scores that can gauge plaque buildup, as well as several different measures of sleep, including wristwatch-assessed sleep across a week and a night in a sleep laboratory that measured electrical brainwave signals.
The final outcome clearly linked disrupted sleep patterns to higher concentrations of circulating inflammatory factors and, specifically, of white blood cells known as monocytes and neutrophils, which are key players in atherosclerosis.
“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,” Walker said.
“To the best of our knowledge, these data are the first to associate sleep fragmentation, inflammation and atherosclerosis in humans,” said study lead author Raphael Vallat.
The findings linking poor sleep to atherosclerosis via chronic inflammation have major public health implications, researchers said.
To more accurately gauge one’s sleep quality, the researchers recommend the use of clinical-grade sleep trackers, because the study found that people’s subjective assessments of their sleep were not reliable.
“This link between fragmented sleep and chronic inflammation may not be limited to heart disease, but could include mental health and neurological disorders, such as major depression and Alzheimer’s disease,” Walker said.
“These are new avenues we must now explore,” the authors wrote.