Why disrupted sleep linked to chronic inflammation, hardened arteries

In a new study, researchers found why disrupted sleep linked to chronic inflammation, hardened arteries.

The research was conducted by a team at the University of California, Berkeley.

Disrupted nightly sleep and clogged arteries tend to sneak up on us as we age.

And while both disorders may seem unrelated, this study helps explain why they are, in fact, pathologically intertwined.

The scientists have begun to reveal what it is about fragmented nightly sleep that leads to the fatty arterial plaque buildup known as atherosclerosis that can result in fatal heart disease.

They have 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.

The findings add poor sleep as a key risk factor for heart disease, which ranks as the top killer of Americans, with some 12,000 deaths each week — although COVID-19, which has killed, on average, 1,000 a day during the pandemic in the U.S., comes close.

Established risk factors for heart disease in humans include a poor diet, lack of exercise, obesity, high blood pressure, and smoking.

Using statistical modeling, the researchers analyzed 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 behaviors such as smoking.

The researchers then tracked the results of the study participants, analyzing 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.

The findings linking poor sleep to atherosclerosis via chronic inflammation have major public health implications.

For example, atherosclerosis often begins in early adulthood. Unfortunately, this process goes largely unnoticed until the plaque buildup, in middle or old age, suddenly blocks arterial blood flow to the heart, lungs, brain and/or other organs, hence its moniker, ‘silent killer’.

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.

Tips to improve sleep quality

  1. Maintain a regular sleep routine, going to bed, and waking up at the same time each day.
  2. As part of a nightly wind-down routine, avoid viewing computers, smartphones, and TV screens in the last hour before bedtime, and keep phones and other digital devices out of the bedroom.
  3. Engage in some form of physical exercise during the day.
  4. Get exposure to natural daylight, especially in the first half of the day.
  5. Avoid stimulants, like caffeine, and sedatives, like alcohol, later in the day.
  6. If you can’t sleep, get out of bed and do a relaxing activity away from the bedroom, such as reading in dim light. Only return to bed when you’re sleepy.
  7. Get screened for sleep apnea if you are known to be a heavy snorer and/or feel excessively tired during the day.
  8. Consult your doctor if you are experiencing insomnia, and inquire about cognitive behavioral therapy for insomnia (CBTI).

One author of the study is Matthew Walker, a UC Berkeley professor of psychology and neuroscience.

The study is published in the journal PLOS Biology.

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