Sleep apnea is often thought of as a sleep disorder that causes snoring and daytime fatigue, but its impact reaches far beyond sleep quality. One of the most serious and underrecognized consequences of untreated sleep apnea is an increased risk of stroke. The relationship between stroke and sleep apnea is complex and bidirectional: sleep apnea raises the risk of stroke, and stroke itself can worsen or even cause sleep apnea.
Understanding this connection is critical for prevention, recovery, and long-term brain and cardiovascular health.
Sleep apnea is a disorder characterized by repeated pauses in breathing during sleep. The two main types are:
Obstructive sleep apnea (OSA): Caused by collapse of the upper airway during sleep
Central sleep apnea (CSA): Caused by impaired signaling from the brain to the respiratory muscles
Both lead to intermittent drops in oxygen levels and repeated sleep fragmentation throughout the night.
Repeated drops in oxygen levels trigger:
Oxidative stress
Endothelial dysfunction
These changes accelerate atherosclerosis and impair blood vessel health, increasing the likelihood of ischemic stroke.
Sleep apnea causes frequent surges in sympathetic nervous system activity, leading to:
Loss of normal nighttime blood pressure dipping
Increased daytime blood pressure variability
Hypertension is the strongest modifiable risk factor for stroke, and sleep apnea makes blood pressure harder to control.
Sleep apnea increases the risk of atrial fibrillation, a major cause of cardioembolic stroke. Mechanisms include:
Atrial stretch from negative intrathoracic pressure
Autonomic instability
Structural and electrical remodeling of the heart
Untreated sleep apnea is associated with higher rates of atrial fibrillation recurrence and stroke.
Sleep apnea disrupts the brain’s ability to regulate blood flow in response to oxygen needs. This impaired autoregulation makes the brain more vulnerable to ischemic injury during periods of reduced perfusion.
The relationship works in both directions. After a stroke:
Brainstem or cortical injury can impair respiratory control
Muscle weakness can increase airway collapse
Reduced mobility and weight gain may worsen OSA
Studies show that a significant proportion of stroke survivors—often more than 50%—have sleep apnea, frequently undiagnosed prior to their stroke.
Untreated sleep apnea after stroke is associated with:
Slower neurological recovery
Worse cognitive outcomes
Increased risk of recurrent stroke
Higher mortality
Sleep fragmentation and nocturnal hypoxia interfere with neuroplasticity, the brain’s ability to rewire and recover after injury.
Treatment—most commonly with continuous positive airway pressure (CPAP)—has been shown to:
Improve blood pressure control
Reduce atrial fibrillation burden
Improve oxygenation and sleep quality
While adherence can be challenging, evidence suggests that consistent treatment of sleep apnea reduces the risk of recurrent stroke and improves functional outcomes after stroke.
Screening is especially important for:
Patients with hypertension that is difficult to control
Individuals with atrial fibrillation
Anyone with a history of stroke or transient ischemic attack (TIA)
Patients with loud snoring, witnessed apneas, or excessive daytime sleepiness
Early identification allows for intervention before irreversible damage occurs.
Sleep apnea is not just a sleep disorder—it is a major, modifiable risk factor for stroke. Its effects on blood pressure, oxygenation, heart rhythm, and vascular health place significant strain on the brain. At the same time, stroke can worsen sleep apnea, creating a dangerous cycle.
Recognizing and treating sleep apnea is a critical component of stroke prevention and recovery, with benefits that extend well beyond improved sleep.
If you or someone you know struggles with sleep, please click the orange button below to take a free online sleep test and talk with one of our sleep health professionals.