You're 80 Percent More Likely to Have a Stroke at This Time, Research Shows

This window of time is the most dangerous of the day.

A stroke occurs when the blood supply to your brain is blocked, stopping oxygen and nutrients from reaching your brain tissue and ultimately killing brain cells. Every forty seconds, someone in the U.S. has a stroke, and every four minutes, someone dies from it, according to the Centers for Disease Control and Prevention (CDC).

Of course, these numbers represent averages, not actual medical emergencies occurring evenly throughout the day. In fact, research shows that the distribution is more uneven than you might think: you're 80 percent more likely to have a stroke during one time of day compared with all the others.

Becoming aware of the riskiest hours for stroke could help you connect the dots to recognize the symptoms sooner. Being extra vigilant to warning signs during those hours—numbness or weakness on one side of the body, confusion, speech or vision problems, dizziness, or a severe headache with no known cause—could literally save your life. Read on to find out when you're most likely to have a stroke, and what you can do to slash your risk!

RELATED: If You Notice This While Walking, It Could Be the First Sign of a Stroke.

You're 80 percent more likely to have a stroke between 6 a.m. and 12 p.m.

Closeup alarm clock having a good day with background happy woman stretching in bed after waking up, sunlight in morning.

According to a study published by the American Heart Association in Stroke, you're nearly 80 percent more likely to have a stroke between 6 a.m. and 12 p.m. than later in the day. "There was a 49 percent increase in stroke of all types between 6 AM and noon, which is a 79 percent increase over the normalized risk of the other 18 hours of the day," the researchers explain. They say that this "morning excess" of strokes is an example of "circadian variation"—differences in risk that vary based on your body's 24-hour cycle of circadian rhythm.

For the study, the team conducted a meta-analysis of 31 publications with primary data from 11,816 stroke patients. "Despite some rather large differences across studies in reported sample size (59 to 1,075), outcomes (fatal versus nonfatal), and types of stroke studied (ischemic versus hemorrhagic versus other), most of the studies showed a similar diurnal pattern of stroke incidence," the researchers say.

Conversely, the team found a 35 percent decrease in strokes occurring between midnight and 6am compared with the other 18 hours of the day.

RELATED: Drinking a Cup of This a Day Can Slash Your Stroke Risk, New Study Says.

The risk for the most common type of stroke is even higher.

woman touching her head, looking nervous
metamorworks / Shutterstock

Because the data was so extensive and varied, the research team was able to analyze time of day as it relates to stroke in several different ways. In one sub-analysis, they isolated different types of strokes to see if they had stronger or weaker correlations to time of day.

What they found was that some types of stroke had a more circadian variation than others, but all types were still more likely to occur in the morning. "The data are remarkably consistent across the various subtypes of stroke, and indicate, for ischemic stroke, hemorrhagic stroke, and even transient ischemic attacks, that the excess risk during the 6 AM to noon time period is significantly higher than would be expected by chance: 89 percent, 52 percent, and 80 percent," the team says.

In other words, the most common type of stroke—ischemic stroke—is not 80, but nearly 90 percent more likely to occur during those early hours of the morning.

Your specific wake time may have an impact.

Black man pictured from behind stretching in bed in the morning, wearing a blue shirt, savory breakfast leads to success study

In discussing the limitations of their study, the AHA researchers noted that they did not adjust the data to account for study subjects' individual wake times. For this reason, they say their study may have failed to capture "strokes occurring among individuals who work night or evening shifts, who have a higher blood pressure on arising but not in the typical 6 to 8 AM time frame."

Other studies have provided evidence to suggest that one's wake time can have a significant impact on when a patient is most likely to have a stroke. For example, one study published in the journal Cerebrovascular Diseases found that your chances of a stroke differ depending on whether you're working or on vacation.

"The onset of ischemic stroke peaked between 6 and 8 a.m. during working days and between 8 and 10 a.m. during [time off]. Strokes occurred more often during the 2 hours following awakening than during any other time of the day," that team explains.

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Taking blood pressure medication at night may help prevent morning stroke.

Man taking pills in bed
iStock/Jelena Danilovic

High blood pressure is considered one of the most significant risk factors for stroke, and regulating blood pressure is key to prevent it, experts say. This is significant because the researchers behind the AHA study note that blood pressure typically rises approximately 20 percent after a person wakes up in the morning. The study's authors say that using medication to "target the early morning rise in blood pressure and heart rate, without reducing blood pressure severely during the night, might be more advantageous" in controlling it.

Another study published in the European Heart Journal concluded that taking hypertension medication at bedtime may cut your stroke risk in half. The study participants who took their medications at bedtime (rather than another time of day) were also 34 percent less likely to have a heart attack, 40 percent less likely to need a procedure to widen clogged arteries, and 42 percent less likely to develop heart failure.

However, the same treatment isn't right for everyone, so talk to your healthcare provider before making any changes to your medication routine.

RELATED: Half of People Who Have a Stroke Notice This a Week Earlier, Study Says.

Lauren Gray
Lauren Gray is a New York-based writer, editor, and consultant. Read more
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