Your stroke risk is 72 per cent higher during these three hours of the day

详细摘要

According to health experts, mornings create a perfect biological storm.

The morning rush often feels like nothing short of a crisis. For our hearts and brains, it’s also the riskiest time of day.

A meta-analysis of almost 12,000 adult stroke patients found that people were 72 per cent more likely to have a stroke between 6 and 9am compared with the remaining 21 hours of the day. Every type of stroke studied saw a morning spike – whether caused by clots, bleeding or even “ministrokes” called transient ischemic attacks.

Heart attacks follow a similar pattern. A separate analysis found that they are 40 per cent more likely to happen between 6am and noon than the rest of the day.

That’s probably because, in many ways, mornings create a perfect biological storm.

In the early hours, melatonin begins to fall and cortisol climbs – peaking shortly after awakening. 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. That elevation in blood pressure raises the risk of heart attacks and strokes.

But in terms of strokes, the issue is not simply blood pressure. It turns out your blood itself changes in the morning too.

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. And a subsequent study found that a blood protein that prevents clots from dissolving also peaks in the morning hours.

Circadian biology affects far more than our energy. It governs the behaviour of many of our bodies’ cells, molecules and even which genes are expressed. And it helps explain why the morning can be a vulnerable time for stroke.

Strokes are medical emergencies that occur when a part of the brain doesn’t receive enough blood – often caused by a blood clot suddenly blocking a vessel or a vessel bursting.

文章开头，摘自The Age。如需阅读全文，请前往媒体网站。