A stroke is defined as the sudden onset of neurological symptoms that result from a disruption in the flow of blood to part of the brain. If a stroke occurs while sleeping, the presence of symptoms after awakening would constitute the signs of a stroke. In this context, it is important to distinguish between a stroke and a transient ischemic attack, or TIA, which some people call a "mini-stroke."
Problems with movement or coordination can indicate a stroke. A sudden weakness or paralysis, particularly when it involves all or part of one side of the body, is an example of such a problem. Strokes often affect the sections of the brain that control movement of the face and tongue, so difficulties with facial expressions, chewing, swallowing or moving the tongue all may indicate that a stroke has occurred. Coordination is another aspect of movement that can be affected by a stroke. Disturbances in gait or balance, dizziness and difficulty performing familiar tasks that require coordination also are consistent with stroke.
Sensation is another brain function that can be disrupted by a stroke. Sudden complete or partial loss of vision, blurred vision, double vision and difficulties with eye movements all are symptoms of sensory disruption. Problems with hearing or the sense of smell also are possible with a stroke. In addition, numbness to pain, touch or temperature, particularly when they affect all or part of one side of the face or body, are signs that a stroke may have occurred.
Problems With Thinking or Cognition
The areas of the brain that control thinking and higher cognition also may be affected by a stroke. Loss of consciousness, confusion, sudden loss of memory and difficulties speaking, understanding speech, writing or reading may be symptoms of a stroke. Sudden severe headache, particularly when accompanied with loss of consciousness or nausea and vomiting, can be a sign that a particularly severe type of stroke may have occurred, although it is unlikely that someone would remain asleep despite these symptoms.
Transient Ischemic Attacks
Like a stroke, a TIA is caused by a disruption of the flow of blood to part of the brain. In a TIA, however, the blood flow returns more or less to normal after a few minutes. Neurological symptoms occur while the blood flow is diminished, but no areas of the brain are significantly damaged, and the symptoms eventually disappear. The neurological symptoms from a TIA typically last five to 15 minutes, but a stroke proper is not considered to have occurred unless they last longer than 24 hours. Depending upon the nature of the symptoms, a TIA that occurs while sleeping might not necessarily cause the individual to wake up. Since the symptoms are likely to disappear by the time the person wakes up, a TIA that occurs during sleep might not have any signs at all. TIAs are highly likely to reoccur, however.
- "Clinical Neurology, 7th ed."; Rodger P. Simon, et. al. (eds); 2009
- "Harrison’s Principles of Internal Medicie, 16th ed."; Dennis L. Kasper, et al. (eds.); 2005