People who have a heart attack in the morning tend to face a tougher recovery than those who have them later in the day and night, according to experts who studied over 800 patients in Spain. The body’s natural sleep-awake cycle could explain the difference, as it’s been well established that a person’s body clock can influence heart attack risk, the BBC reports. For example, people are more likely to have a heart attack when they’re waking up. Researchers looked at 811 patients who’d suffered a heart attack with a prolonged period of blocked blood supply to the heart muscle (called ST elevation myocardial infarction), and split them into four groups according to when it occurred. Those who suffered a heart attack from 6 am to noon had the most severe attacks, with higher levels of an enzyme in the blood, which is a signal of dying heart tissue. Researchers estimated the area of heart damaged in this group was one-fifth larger on average.