Why Insomnia May Raise Stroke Risk
While researchers don’t completely understand why insomnia may increase stroke risk, Vignatelli offers a few potential explanations.
It’s possible that persistent sleep trouble puts the body into a constant stress response, he says, overactivating the same systems involved in a fight-or-flight reaction. That raises blood pressure, heart rate, and tension in blood vessel walls.
As a result, the stress hormone cortisol stays elevated, which can raise blood pressure further, fuel inflammation throughout the body, and disrupt how the body processes sugar and fat. Over time, that combination can contribute to plaque building up inside artery walls.
That inflammation can also make existing plaque more likely to rupture and form blood clots. It can damage the lining of blood vessels too, throwing off the balance between vessels relaxing and tightening the way they’re supposed to.
Insomnia can also throw off the hormones that regulate appetite, contributing to weight gain, and can impair the body’s ability to manage blood sugar and fat. Over time, those changes can lead to obesity and damage to small blood vessels, both of which make the brain more vulnerable to stroke.
Sleep Plays a Direct Role in Protecting the Brain
Sleep itself plays a direct role in protecting the brain, says Karin Johnson, MD, professor of neurology at UMass Chan Medical School and division chief of Baystate Sleep Medicine in the department of neurology in Springfield, Massachusetts, who was not involved in the study.
“Healthy sleep helps clear waste from the brain through what’s known as the glymphatic system, a process considered especially important for preventing Alzheimer’s and other neurodegenerative diseases,” says Dr. Johnson.
Blood pressure normally drops during healthy sleep, she says, but in sleep disorders like obstructive sleep apnea, it can rise instead, adding wear on blood vessels over time.
Strengths and Limitations of the Study
The review’s biggest strength is its scope: It draws on decades of research across seven distinct health outcomes, including two new analyses on stroke and hospitalization that hadn’t been done before.
But the researchers note that studies varied widely in how they defined insomnia, and few accounted for whether participants were using sleep medications, which could affect the results.
Because of the studies and type of data included, the review shows correlation (meaning a possible link for which there could be multiple explanations), not cause-and-effect, says Johnson. Researchers still need studies confirming whether treating insomnia actually lowers stroke risk, and whether treatments like medication or cognitive behavioral therapy work equally well, she says.
How to Protect Your Sleep and Your Brain
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Here are the AHA’s tips for getting the recommended seven to nine hours of sleep a night:
Watch your light exposure. Dim the lights in the evening to help your brain start winding down and consider a red-light filter or dimmed screens at night, since blue light can suppress the melatonin your body needs to fall asleep.
Keep a consistent schedule. Going to bed and waking up at the same time every day helps regulate your internal clock, and a bedtime alarm can help you remember when it’s time to start wrapping up for the night.
Build in a wind-down window. Spend 20 to 30 minutes before bed on a calming, screen-free activity, like reading, meditating, or taking a warm bath.
Silence your phone. Put it on do-not-disturb overnight so notifications don’t wake you or keep you from settling down.
