A stroke can be debilitating or deadly—more than six million people worldwide died of strokes in 2019, according to the American Heart Association—and being aware of the early symptoms can mean the difference between life and death. Certain telltale stroke symptoms are more commonly known than others, such as a sudden feeling of numbness or weakness on one side of the body, as well as confusion and difficulty speaking, as per the Centers for Disease Control (CDC). Other possible signs of stroke can be surprising. One particular symptom that you may experience upon waking in the morning could signal the onset of a stroke, and warrants immediate medical attention. Read on to find out what to watch for.
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Strokes can occur for different reasons.
"Each year approximately 795,000 Americans have a stroke, with about 160,000 dying from stroke-related causes," says the National Institute of Neurological Disorders and Stroke (NINDS), which also notes that stroke is the most common reason for adult disability, as well as the fourth-leading killer in the United States.
Strokes have two main causes, the Mayo Clinic reports: a blocked artery (ischemic stroke) or leaking or bursting of a blood vessel (hemorrhagic stroke). Ischemic stroke is the most common type, and occurs when "the brain's blood vessels become narrowed or blocked, causing severely reduced blood flow (ischemia)." In the case of a hemorrhagic stroke, the blood vessel in the brain is ruptured, causing it to leak.
Strokes can occur in the eye as well as in the brain.
Strokes don't only occur in the brain. Another type of stroke, called retinal artery occlusion, happens in the eye, and is also known as an eye stroke.
"The strokes we commonly think of in the brain lead to some weakness or slurred speech, or loss of consciousness," explains cardiac surgeon Allan Stewart, MD, FACS, FACC. "The reason these symptoms occur is that an artery supplying blood to a portion of the brain becomes blocked, by either a clot that acts somewhat like a cork, obstructing blood flow, or an artery becomes too narrow to allow free passage of blood."
Stewart says the same type of event can happen in the eye, resulting in a loss of blood flow to the retina, which he describes as "the portion of the eye that interacts with the brain and creates sight." When the flow of blood is disrupted, "there is an immediate loss of sight, and damage can rapidly occur," Stewart notes.
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An eye stroke may present as this change in your vision.
Many different kinds of vision changes may signal various health conditions that you might not necessarily associate with the eyes. Blurry vision, for example, can be a warning sign of multiple sclerosis, and a decrease in peripheral vision could signal the onset of Alzheimer's disease.
"Symptoms of eye stroke can appear somewhat benign, as small 'floaters' in the eye, meaning small areas of floating blackness," says Stewart. But loss of vision in the morning can be another symptom of eye stroke.
If you wake up with decreased vision, with or without pain, call your doctor. "It is important to recognize that, when the problem is due to an eye stroke and not a brain stroke, the symptoms present in only one eye," notes Stewart.
Other types of vision changes may indicate an eye stroke.
A stroke can occur with seemingly little warning, which is why it's important for people to know the early symptoms.
"Most people with eye stroke notice a loss of vision in one eye upon waking in the morning with no pain," according to Penn Medicine. "Some people notice a dark area or shadow in their vision that affects the upper or lower half of their visual field. Other symptoms include loss of visual contrast and light sensitivity."
Vision loss at any time of the day or night is cause for concern, but since people are 80 percent more likely to have a stroke between the hours of 6 a.m. and 12 p.m., according to the American Heart Association, waking up with this issue is a red flag. If you notice it, seek medical attention as soon as possible.