According to a new study, sleep disturbance symptoms, sleep quality, napping for long periods, and sleep apnea symptoms are associated with an increased risk of acute stroke.
The study's findings highlight the importance of getting the right amount of sleep every night, which the study suggests is between five to nine hours.
A study published in Neurology, the medical journal of the American Academy of Neurology, found that sleeping disturbance symptoms are associated with an increased risk of acute stroke.
Acute strokes are either classified as ischemic (when blood vessel blockages limit blood supply to the brain) or hemorrhagic (when blood vessels rupture and spill blood into the intracranial cavity). According to the National Heart, Lung, and Blood Institute, 50 to 70 million people in the United States have a sleep disorder, making the study’s findings especially critical.
The study, Interstroke, focused on 4,496 subjects—including 1,799 who’d had an ischemic stroke and 439 who had an intracerebral hemorrhage (ICH). The remainder were control subjects individually matched—near the same age (give or take five years) and sex—to each subject with a stroke. The average age for all of the subjects was 62.
The researchers also looked at variables such as occupation, marital status, stress levels, activity levels, alcohol consumption and disease risk factors.
In order to assess the individuals with a stroke, the study required subjects to answer a detailed questionnaire regarding their sleep symptoms in the month prior to the stroke. Proxies were utilized for patients with severe stroke and aphasia to fill out the questionnaire.
The study’s findings
The researchers found multiple sleep disturbance symptoms were significantly associated with acute stroke. They include:
Short or long sleep: Sleeping less than five or more than nine hours was associated with an increased risk of stroke. The researchers also noted one specific connection between ethnicity and stroke risk. For people in South Asia and with South Asian ethnicity who reported short sleep, the study found the highest risk of stroke. However, long sleep duration and stroke remained significant across all ethnic and regional subgroups.
Impaired sleep quality: Poor or fair sleep quality (self-reported) and frequent waking were both associated with an increased risk of stroke.
Prolonged napping: The authors found that long naps (over one hour) were associated with significantly increased odds of all strokes; short naps were not.
Obstructive sleep apnea symptoms, like snoring, snorting, and breathing cessation: Self-reported snoring, snorting, and breathing cessation were associated with a statistically significant increased risk of stroke, even with every variable of adjustment. In fact, people who snore were found to be 91 percent more likely to have a stroke than non-snorers, while snorting and sleep apnea were associated with a three-fold risk of stroke. There was no difference in ICH versus ischemic stroke in this case.
Other sleep disturbances associated with an increased risk of stroke include difficulty getting to sleep, difficulty maintaining sleep, and unplanned napping. Additionally, the study found that individuals with five or more of the above symptoms were at even greater risk of stroke. “The magnitude of association was additive, with a graded increase in odds of acute stroke, for cumulative increase in sleep symptoms, with consistent findings for ischemic stroke and ICH,” the authors wrote.
What sets this study apart?
The study’s authors aimed to consider a wider breadth of variables than previous studies had focused on, they say.
Firstly, it acknowledged the already-clear association between nocturnal waking and obstructive sleep apnoea (OSA) and stroke. Therefore, the authors underscored the fact that connections between other sleep disorders (like long or short sleep) and stroke tend to be less well-documented. Additionally, it aimed its focus on a wide breadth of international subjects rather than single populations.
The study’s limitations
The study’s limitations include the fact that the subjects (or their proxies) self-reported their sleeping symptoms. “Our assessments of sleep practices were similar to previous research in this area, however, and undertaking a prolonged sleep questionnaire would not have been possible in the context of this multifaceted study,” the authors wrote. The authors also noted that subjects may have had trouble with recall bias and memory, with stroke patients often using the “I don’t know” option to answer questions. To compensate for this, the researchers aimed to have patients answer questions within 72 hours of a stroke. Additionally, they had patients answer questions regarding a shorter time frame.
The authors also cited limited assessment around ethnicity and stroke risk as well as the risk of healthy volunteer bias as limitations. Lastly, the study’s authors noted that they were unable to adjust the analysis to consider shift work, sedative use, and statistics around undiagnosed obstructive sleep apnea.
What this information means for patients
Overall, the message is clear: Sleep is undoubtedly entwined with health. “Our results suggest that sleep problems should be an area of focus for stroke prevention. With these results, doctors could have earlier conversations with people who are having sleep problems. Interventions to improve sleep may also reduce the risk of stroke and should be the subject of future research,” Christine Mc Carthy, MB, BCh, BAO, of University of Galway in Ireland, one of the study’s authors, told Newswise,
Mitchell Levine, DMD, president of the American Academy of Dental Sleep Medicine (AADSM), agrees that the study’s findings were illuminating.
Beyond providing information about specific sleeping issues like snoring, the study helps illuminate other issues, like the impact of too little sleep or too much—something many people experience due to work or stress, Levine adds. “Important information like this further confirms that getting the right amount of sleep every night is an essential pillar to health,” he says.
Levine notes that sleep issues also go beyond stroke, however. “The sleep community has [also] been aware of cardiovascular concerns, as well as metabolic and neurological challenges found in those who snore with or without sleep apnea,” he adds. Because of this, Levine says that you should discuss sleep hygiene with your patients during care visits—and that you should empower them to bring up any concerns they may have.
That said, caring for a patient’s sleep health takes a village. “This information also conveys the importance of a collective, interdisciplinary approach to managing sleep disorders,” Levine says. “In addition to physicians, care teams such as nurses, qualified dentists, psychologists, and durable medical equipment (DME) suppliers play an important role in managing sleep care.”