A meta-analysis of nearly 12,000 adult stroke patients has found that the risk of having a stroke is 72 per cent higher between 6am and 9am than during the rest of the day. The spike was seen in every type of stroke studied, including those caused by clots, bleeding and ministrokes.
Heart attacks follow a similar pattern. A separate analysis found they are 40 per cent more likely between 6am and noon than at other times.
The timing is linked to circadian rhythms. In the early morning, melatonin begins to fall and cortisol climbs, peaking shortly after awakening. Blood pressure, which dips by 10 to 20 per cent of its daytime baseline during sleep, starts to rise before waking and surges upon rising. Research from 2011 found that platelets become more likely to clump together in the early morning, and a later study found that a protein that prevents clots from dissolving also peaks in the morning.
Recognising stroke symptoms quickly is critical. While familiar signs include slurred speech and a drooping face, about one in seven stroke patients had none of those symptoms. Instead, many experienced sudden trouble with balance or loss of vision. The American Stroke Association recommends the mnemonic BE FAST: Balance, Eye changes, Face drooping, Arm weakness, Speech difficulty, Time to call 000.
Emergency doctors will ask when the patient was 'last seen well' because the window for mechanical clot removal has widened. In 2018, major trials found compelling evidence for extending it beyond six hours. For some patients, clots can be removed up to 24 hours after the stroke started. The clot-dissolving drug tPA is generally not given beyond four and a half hours.
Blood pressure medication timing has been considered in relation to the morning surge. Two independent trials, one in the United Kingdom and one in Canada, found that bedtime dosing did not lead to a difference in heart attacks, strokes or deaths. In the Canadian trial, bedtime dosing was associated with lower adherence. For people whose medication caused them to urinate more often, taking it before bed meant disrupting their sleep. The article advises that the best time is the time taken consistently, and recommends checking blood pressure at home, including morning readings before medication.
Analysis
Why This Matters
- Stroke is a leading cause of death in Australia; understanding peak risk hours can inform prevention strategies.
- The findings highlight the importance of morning blood pressure monitoring and consistent medication use.
- Awareness of less common stroke symptoms, such as balance problems or vision loss, could lead to faster treatment and better outcomes.
Background
Circadian rhythms regulate many bodily functions, including blood pressure and blood clotting. The morning surge in stroke and heart attack risk has been documented in multiple studies. The treatment window for stroke has expanded: mechanical clot removal can now be performed up to 24 hours after onset, extending the previous six-hour limit.
What to Watch
- Whether further research confirms the circadian mechanisms at play and suggests lifestyle adjustments.
- Public health campaigns may increasingly promote BE FAST and encourage home blood pressure monitoring.
Checked
12 claims in this story checked against 1 source: 12 supported.
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- SupportedStroke risk is 72 per cent higher between 6am and 9am than during the rest of the day.Brisbane Times - Latest News: “people were 72 per cent more likely to have a stroke between 6 and 9am compared with the remaining 21 hours of the day.”
- SupportedA meta-analysis of almost 12,000 adult stroke patients found the increased morning stroke risk.Brisbane Times - Latest News: “A meta-analysis of almost 12,000 adult stroke patients found that people were 72 per cent more likely to have a stroke”
- SupportedThe morning spike was seen in every type of stroke studied, including strokes caused by clots, bleeding and ministrokes.Brisbane Times - Latest News: “Every type of stroke studied saw a morning spike – whether caused by clots, bleeding or even “ministrokes” called transient ischemic attacks.”
- SupportedHeart attacks are 40 per cent more likely between 6am and noon than during the rest of the day.Brisbane Times - Latest News: “A separate analysis found that they are 40 per cent more likely to happen between 6am and noon than the rest of the day.”
- SupportedBlood pressure dips by 10 to 20 per cent of its daytime baseline during sleep, begins rising before waking and surges after getting up.Brisbane Times - Latest News: “While you sleep, blood pressure tends to dip by around 10 to 20 per cent of your daytime baseline, then starts to rise just before you wake up. Once you get up and start moving, blood pressure surges.”
- SupportedA 2011 study found that platelets become more likely to clump together in the early morning.Brisbane Times - Latest News: “In 2011, researchers from Boston found that our circadian rhythm drives platelets – small cell fragments that form blood clots – to become more likely to clump together in the early morning.”
- SupportedAbout one in seven stroke patients in one study had none of the familiar symptoms described.Brisbane Times - Latest News: “But in one study, about one in seven stroke patients had none of those symptoms.”
- SupportedMany people having strokes experienced sudden trouble with balance or loss of vision.Brisbane Times - Latest News: “Instead, many people having strokes experienced sudden trouble keeping balance or loss of vision.”
- SupportedEmergency doctors will ask when the patient was “last seen well”.Brisbane Times - Latest News: “Emergency room doctors will want to know – either from you or a family member – when you were “last seen well”.”
- SupportedFor some patients, clots can be removed up to 24 hours after the stroke started.Brisbane Times - Latest News: “today, for some patients, clots can be removed up to 24 hours after the stroke started.”
- SupportedThe clot-dissolving drug tPA is generally not given beyond four and a half hours.Brisbane Times - Latest News: “So while tPA is generally still not given past the four and a half hour window”
- SupportedThe article advises taking blood pressure medication at the time a person can take it consistently.Brisbane Times - Latest News: “the best time to take your blood pressure medication is the time you’ll take it consistently”
