Getting a good night's sleep can be difficult for many, but restful slumber can be especially hard for stroke survivors. And although various studies have examined the association, doctors continue to overlook the interplay between sleep disorders and stroke, finds a new report on the issue.
More than 50% of stroke survivors are estimated to have some type of sleep problem, yet few get formally tested, in part because of "the lack of awareness" among stroke providers, according to the review published in the American Heart Association journal Stroke.
Gasping for air
In addition to increasing stroke risk, sleep disturbances may worsen after a stroke, the report said. So, remedies to reduce sleep impairments could help prevent a first or subsequent stroke.
Sleep apnoea is a condition in which breathing is repeatedly stopped and restarted because of changes in airflow. The report said more than 70% of stroke survivors have a specific condition known as obstructive sleep apnoea, in which the tongue or other obstruction blocks airway in the throat.
This can cause a person to snore or to stop breathing entirely for several seconds before gasping for air, disrupting sleep in the process. One study cited in the new report found people with obstructive sleep apnoea had a nearly twofold increase in stroke or death.
People with severe cases of obstructive sleep apnoea may find their sleep interrupted more than 30 times per hour, said Dr Sandeep Khot, the report's senior author and an associate professor of neurology at the University of Washington School of Medicine in Seattle.
High blood pressure
"You end up with what we call fragmented sleep. Your sleep is fitful because you never really get into slow-wave sleep or REM sleep, the deeper types of sleep that are associated with feeling refreshed the next day. This may affect your recovery from stroke, along with the physiologic changes that happen with your body, especially blood pressure changes," Khot said.
It can particularly lead to high blood pressure, or hypertension. That may be a reason why some doctors miss the connection between sleep disorders and stroke, said epidemiologist Donna Arnett, dean of the University of Kentucky College of Public Health.
High blood pressure is the strongest risk factor for stroke, but another big contributor is obesity, and both are strongly associated with sleep apnoea, she said.
"Most clinicians caring for stroke patients have probably thought that it's the hypertension and the obesity that are the causal factors for stroke and they may have missed the association with sleep apnoea," said Arnett, who was not involved in the review.
Continuous positive airway pressure, or CPAP, has been deemed "the gold standard of treatment" for obstructive sleep apnoea. But many people consider CPAP treatment, which involves wearing a mask during sleep, challenging and don't always use it.
Simple questions about sleep
While there are other treatments available for sleep apnoea, Khot said CPAP is the primary one for stroke survivors. "We really have to have an open mind on who may and may not tolerate the treatment."
Khot said a large study, called Sleep SMART, is currently recruiting patients and will examine the impact of CPAP treatment for people who have either had a stroke or a high-risk TIA, a transient ischaemic attack often called a mini-stroke. The study will look at the treatment's ability to prevent a second stroke, as well as recovery from the first one.
For now, he'd like to see more health care providers who work with stroke survivors start incorporating questions about sleep patterns into visits.
"We think of the traditional risk factors for having another stroke or vascular event – hypertension, diabetes, cholesterol, smoking. But most of us don't ask about sleep apnoea," Khot said. "Just simple questions about sleep. And if you have someone who has had a stroke, consider a low threshold for sending them to a sleep centre for testing."
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