Medically reviewed by
Dacelin St Martin, MD
Triple board-certified in Sleep Medicine,
Internal Medicine, and Pediatrics.
Can sleep lead to a stroke? Scientists say it just might! The brain is a fascinating organ – it controls memories, thoughts, emotions, body functions, movements, and speech. But a single stroke can put an end to all of that.
A stroke happens when blood flow to the brain is interrupted by a clot or a rupture in a blood vessel. That can cause physical disabilities, paralysis, and even death. We already know that high blood pressure, diabetes, and smoking can increase the risk of stroke. Scientists now say that the amount of sleep we get each night may also play a role.
What’s the Link Between Sleep and Stroke?
Not many people may know what Whipple’s Disease is, but most adults are familiar with strokes. That’s because stroke is one of the leading causes of death and disability worldwide.
So it comes as no surprise that scientists are equally interested in strokes and what causes them.
Back in 1987, researchers found a link between snoring and the risk of stroke. In their study, men who snored during sleep had a higher risk of stroke than non-snorers.
Sleep Disorders and Stroke Risk
In 2000, researchers surveyed patients in a rehabilitation center after their first stroke. They found that many stroke patients also had obstructive sleep apnea (OSA), a common sleep disorder that often causes loud snoring. Their data also suggested that those patients may have had unusual sleep patterns before the stroke.
Later in 2002, scientists found evidence that strokes can cause sleep changes, such as insomnia (trouble falling asleep or staying asleep) and hypersomnia (sleeping longer than usual at night). At that point, they still weren’t sure whether sleep problems increase a person’s risk of stroke or if it’s the stroke that causes sleep disorders.
Finally, in 2005, researchers found strong evidence that people often have sleep disorders – like sleep apnea – before a stroke, and those disorders can increase the risk of stroke. They tracked thousands of patients over the years and noticed that people with sleep apnea were likelier to have a stroke than those without sleep apnea.
In the following years, several studies further confirmed that sleep apnea and other sleep disturbances significantly increase the risk of stroke whether a person has high blood pressure (a risk factor for stroke) or not.
Sleep Duration & Stroke Risk
To dive deeper into the matter, scientists needed to know whether it’s just interrupted sleep or the hours of sleep individuals get each night that affects their chances of getting a stroke.
Fast forward to 2019, researchers monitored 31,750 individuals. They found that people who slept more than nine hours per night had a higher risk of stroke than people who slept 7-8 hours each night. They added that people with long midday naps and poor sleep quality were also more likely to get a stroke.
Another study also found that individuals who slept less than 5 hours a day (short sleep duration) and those who slept more than 9 hours a day (long sleep duration) had a higher risk of dying from a stroke than those who slept 7-8 hours a day. And the risk was highest among people with unusual sleeping hours and high blood pressure.
More recently, an international study found additional evidence that short sleep hours (<5 hours each night), long sleep hours (>9 hours each night), snoring during sleep, and obstructive sleep apnea (OSA) are all associated with increased stroke risk.
Sleep Duration & Type of Stroke
Researchers also wanted to know if the number of hours of sleep a person gets is related to a specific type of stroke: Ischemic stroke, a blood clot that blocks a blood vessel in the brain, or intracerebral hemorrhage, a ruptured blood vessel in the brain that bleeds into the tissue.
They observed 79,881 women and men with different sleep durations and got their answers: People who sleep too much (≥9 hours per day) had a higher risk for ischemic stroke, while those who don’t get enough sleep (<7 hours per day) had a higher risk for intracerebral hemorrhage.
Does Less Or More Sleep Cause Stroke?
Although all these studies point to a strong link between sleep duration and the risk of stroke, they don’t prove that not getting enough sleep or sleeping too much can cause a stroke.
These findings tell us that people who don’t sleep well have a higher chance of getting a stroke, not that poor sleep quality directly causes a stroke.
How do scientists explain this link? They have a few solid theories.
1) A Common Cause
One possible explanation is that certain health conditions that increase the risk of stroke – such as diabetes and high blood pressure – can also cause sleep problems.
Studies show that diabetes can affect a person’s sleeping habits, and people with high blood pressure often have trouble sleeping.
Therefore, sleeping too much or not enough may not directly cause a stroke. Instead, it could indicate an underlying health problem – such as heart disease or diabetes – that increases the risk of stroke.
2) Sleep Duration and Blood Pressure
Another theory is that short and long sleep durations can increase blood pressure – a risk factor for stroke.
A study found that people who sleep less than 7 hours (short sleeping hours) or more than 8 hours (long sleep hours) per night had higher blood pressure than those who sleep 7-8 hours per night.
So, a stroke might happen because of high blood pressure caused by poor sleep.
3) Sleep Duration and Diabetes
A different theory is that short and long sleeping times can increase the risk of diabetes – another risk factor for stroke.
In one study, researchers showed that sleeping less than 6 hours each night (compared to 7 hours) can increase the risk of type 2 diabetes by almost 30 percent.
Another study showed that sleeping less than 6 hours or more than 9 hours per night is a risk factor for type 2 diabetes.
These studies suggest that short or long sleep durations can increase the risk of diabetes and (consequently) stroke.
It is also possible that the relationship between sleep duration and stroke risk is bidirectional: Stroke could disrupt sleep patterns, leading to changes in sleep hours, while too much or insufficient sleep can cause health problems that could lead to a stroke.
Scientists are still trying to understand the complex dynamics that tie sleep durations to stroke.
While many studies propose that short and long sleeping hours may increase the risk of stroke, others suggest that you may be sleeping for long hours or not getting enough sleep because of an underlying health condition that could eventually cause a stroke.
Further research is needed to unravel this relationship and identify what people can do to reduce their risk of stroke.
Many scientific studies have proved that good sleep is essential for physical and mental health, and we should prioritize adequate sleep as part of a healthy lifestyle. If that also helps us avoid having a stroke in the future, we win the jackpot!
In the meantime, you should contact your healthcare professional if you’re having trouble sleeping or sleeping too much.
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