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A person can go to bed feeling well and wake up with slurred speech, weakness or blurred vision. These symptoms may indicate a stroke that occurred during sleep. Recognising them quickly is essential, even when the exact time of onset is unknown.
Why Do Strokes Happen During Sleep?
A stroke occurs when blood flow to part of the brain is interrupted by a blockage, known as an ischemic stroke, or when a blood vessel ruptures, causing bleeding. During sleep, symptoms may go unnoticed until the person wakes up. These are often called wake-up strokes.
The timing matters. The last known well time refers to the last time a person was known to be free of stroke symptoms, often before going to bed. Although the actual onset may be uncertain, brain imaging and clinical assessment can help determine whether treatment is possible. An unknown onset time does not automatically rule out treatment.
Recognising the Warning Signs
The BEFAST framework helps identify common stroke symptoms:
- Balance: Sudden loss of balance, dizziness or difficulty walking
- Eyes: Sudden blurred vision, double vision or loss of vision
- Face: One side of the face droops when smiling
- Arms: One arm feels weak or drifts downward
- Speech: Speech becomes slurred or difficult to understand
- Time: Call emergency services immediately if any of these symptoms occur
Other warning signs include sudden numbness, confusion, vision loss, a severe headache, dizziness or loss of balance. A transient ischemic attack (TIA), sometimes called a mini-stroke, causes temporary stroke-like symptoms and also requires urgent medical assessment.
Any sudden neurological symptom noticed on waking should be treated as an emergency, even if it improves. Record when the symptom was first noticed and when the person was last known to be well. Do not wait for symptoms to resolve.
READ | High Blood Pressure Without Symptoms: The Silent Risk Factor Behind Many Strokes
What Raises the Risk?
Uncontrolled hypertension, or high blood pressure, is a major risk factor. Diabetes, high cholesterol and smoking also increase the likelihood of stroke. Atrial fibrillation, an irregular heart rhythm that can lead to clot formation, is another important risk factor.
Obstructive sleep apnoea, in which breathing repeatedly stops during sleep, is associated with increased cardiovascular risk. Blood pressure also rises naturally towards morning, potentially adding to risk in susceptible individuals. Poor sleep quality may further affect blood pressure and metabolic health.
Treatment and Recovery
Eligible patients may receive thrombolysis, medication that dissolves blood clots, within a defined treatment window. Mechanical thrombectomy uses a catheter to remove a clot from a blocked large blood vessel. Selected patients with wake-up strokes may qualify following specialised brain imaging.
Rehabilitation, including physiotherapy, speech therapy and occupational therapy, helps address difficulties with movement, communication and daily activities.
READ | Not Just Seniors: Stroke Rates Double In Adults Under 55, Finds New Study
Common Misconceptions About Stroke
- Stroke only affects older people: It can occur at any age
- Symptoms can be slept off: Delaying assessment may reduce treatment options
- Every stroke causes paralysis: Some strokes mainly affect speech, vision, balance or thinking
Reducing the Risk
Maintain a regular sleep routine, monitor blood pressure, exercise regularly, follow a balanced diet, avoid smoking and attend routine health checkups. Persistent loud snoring or pauses in breathing during sleep warrant medical evaluation.
A sudden change in speech, movement, vision or balance on waking is never something to wait out. Immediate medical assessment can help preserve treatment options and improve the chances of recovery.
(By Dr PN Renjen, Senior Consultant, Neurology, Indraprastha Apollo Hospital, Delhi)
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