Struggling to Sleep? Your Brain Health Might Be at Risk

People who consistently struggle to sleep at night may face a greater likelihood of serious issues related to brain health and mental health, according to a large new review of the evidence.

“Insomnia deserves attention as a warning sign of the status of brain and mental health,” says lead author Luca Vignatelli, MD, PhD, a researcher at IRCCS Istituto delle Scienze Neurologiche di Bologna in Italy.

The findings show a link not just between insomnia and stroke but also between insomnia and dementia, as well as mental health conditions like depression and suicidal behavior, he says.

“Insomnia should be recognized and addressed as part of a wider approach to health to reduce the risk of developing these disorders,” says Dr. Vignatelli.

Insomnia Was Linked to Stroke, Hospitalization, and Other Brain Health Issues

For the new research review, investigators searched two major medical databases through August 2025, pulling together existing research on insomnia’s links to seven health outcomes, including dementia, stroke, depression, suicide, and hospitalization. For topics without existing research to pull from, like stroke and hospitalization, they conducted their own new analyses.

Nine studies covering more than 1.3 million people were eligible for the stroke analysis, six of which were included in the final meta-analysis. Hospitalization was assessed across five studies, three of which made it into that meta-analysis.

In addition to the observations on stroke and hospitalization, the review’s other main findings included:

• Dementia risk was elevated in most of the reviews examined, though results were inconsistent; the link was strongest and most consistent for Alzheimer’s disease, while findings on vascular dementia were mixed.
• Depression risk was more than tripled in people with insomnia.
• Suicide death, attempts, and thoughts of suicide were all more common among people with insomnia.
• Death from any cause was not linked to insomnia, and there wasn’t enough evidence to draw conclusions about occupational injuries.

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

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.