Why heart attacks strike early morning, and what cardiologists say you can do to reduce the risk

Another important factor is how blood behaves in the early hours.

Research supported by the National Heart, Lung, and Blood Institute (NHLBI) shows that platelets, the cells responsible for clotting, become more active in the morning.

This makes the blood slightly more prone to forming clots.

Dr Mukesh Goel explains how this interacts with existing heart problems, “At the same time, our blood becomes slightly more prone to clots, which increases the risk of a heart attack occurring. In people who have underlying conditions like hypertension, diabetes, high cholesterol, smoking, and heart disease, these changes act as a trigger for heart attacks.”

If an artery already contains fatty plaque, the increased pressure and clotting tendency can block blood flow to the heart. That blockage is what causes a heart attack.