Sleep apnea sufferers already know the side effects of a poor night’s sleep. Fatigue, inability to concentrate, moodiness, and a morning headache are familiar consequences of sleep disordered breathing. While the symptoms of sleep apnea are nothing to take lightly, there are other potential health risks that you may not even realize. The relationship between sleep apnea and stroke is real, and it could prove fatal.
Can sleep apnea cause strokes?
Sleep apnea is a form of sleep disordered breathing that affects an estimated 25 million people in the U.S. Obstructive sleep apnea is the most common of the three types (which also include central and complex sleep apnea), but any type of severe sleep apnea is associated with an increased risk of stroke.
During a sleep apnea, the sleeper stops breathing, anywhere from ten to 20 seconds. As oxygen levels drop in the brain, the central nervous system recognizes the deficit and wakes the sleeper enough to allow the airway to open and the sleeper to breathe. This cycle can repeat itself all night long, anywhere from five to 20 times an hour.
As noted above, common symptoms of sleep apnea include:
- Daytime fatigue
- Lack of mental clarity
- Difficulty concentrating
- Dry mouth in the morning
Obesity and high blood pressure are risk factors for sleep apnea. They are also risk factors for a potentially deadly condition: stroke.
Stroke is the second leading cause of death in the world, and sleep apnea increases the risk of stroke significantly. In men with sleep apnea, a 2010 study found that stroke risk is more than doubled, with the risk increasing with more severe sleep apnea symptoms. A 2013 study confirmed these results, adding that sleep apnea increased the risk of cardiovascular disease, which itself increased the risk of stroke.
In between these studies, more bad news: stroke in patients with sleep apnea leads more often to death or poor chances of recovery.
Why are sleep apnea and stroke risks related?
Nearly 70% of first-time ischemic stroke patients have sleep apnea, showing that this can be a dangerous duo.
Dr. Melissa Lipford, a neurologist at the Center for Sleep Medicine at Mayo Clinic in Minnesota, explains one reason why the risk of stroke increases in people with sleep apnea:
“During an apneic episode, the body asserts an amazing amount of effort to try to open the airway and get a breath in. Unfortunately, this effort frequently fails to supply the brain with the oxygen it needs to keep the entire body and all its systems working smoothly as you sleep.”
In a healthy sleeper, the inhalation of oxygen is accompanied by the exhalation of carbon dioxide. Without this exchange of gases, carbon dioxide builds to unhealthy levels in the bloodstream. Excess carbon dioxide leads to excessive blood flow in the brain, leading to high blood pressure. High blood pressure increases the risk of stroke.
There is also some evidence that inflammation in the brain due to sleep apnea may contribute to the increased risk of stroke. The complicating factor is the increased inflammation is also causing more incidence of cardiovascular complications due to sleep apnea. It’s challenging for researchers to know if the inflammation comes from the cardiovascular complications and then leads to stroke, or if the inflammation is present only in people with stroke.
Sleep apnea and other cardiovascular issues
It is clear that sleep apnea and stroke are related to sleep apnea and cardiovascular issues, and that both can be fatal. As with all complicated studies of the brain, more research can help truly answer these questions. What’s clear is that people with sleep apnea are three times more likely to prematurely die of any cause than those without sleep apnea.
We know all this through research studies and evidence. In reality, though, many people are walking around with undiagnosed sleep apnea. Indeed, some people are misdiagnosed with depression and anxiety or ADHD instead of sleep apnea. Undiagnosed and untreated sleep apnea can cause sudden death from stroke or cardiovascular illness.