Ibanez collected for the study of 811 patients who had heart attacks between 2003 and 2009. In particular, they analyzed the amount of myocardial damage in relation to a heart attack occurs.

The researchers found that the greatest damage occurred when the heart attack was carried out between 6 am and noon, compared with which the attack took place between 18 pm and midnight.

Ibanez team determines the amount of damage to the heart muscle by looking at the sum of two enzymes released during the attack - creatine kinase and troponin-I. Individuals whose heart attack occurred in the morning had more than 21 percent of these enzymes compared with those whose attack came at the end of the day, they said.

Among the 269 patients studied had heart attacks morning, 240 had their attack in the afternoon, 161 had a heart attack between 6 am and midnight and 141 had an attack between midnight and sixth Sunday work

In addition, because of attacks that took place in the rear wall of prejudice more heart than heart attacks in other parts of the heart, they found.

The results are of great importance, "said Ibanez. "In terms of treatment, when heart attacks occur in the early morning hours, more aggressive treatment of the case could lead to better results," he said.

Moreover, given that heart attacks in the morning cause more damage to the heart can help in developing new drugs that could target specific causes of these attacks, "said Ibanez.

Dr. Gregg Fonarow, deputy chief of cardiology at UCLA School of Medicine David Geffen, said that "there is a circadian variation in the incidence of heart attacks, with a higher incidence of the transition period Sleep to wake. "

This circadian rhythm may include changes in the nervous system, cortisol levels and other factors, the risk of heart attack. There may be differences in circadian rhythms of functions such as heart cells, "he said.

"Regardless of the time, to achieve timely reperfusion of blood to the formation of blood clots or dissolve in coronary patients with myocardial infarction is critical," Fonarow said.