The daily rhythm of heart attack morbidity and mortality may be influenced by the time of sunrise

Abstract

The morbidity and mortality of a myocardial infarction show characteristic seasonal and diurnal changes that may be influenced by the time of sunrise and the number of hours with daylight during the day. We wish to study whether the time of sunrise and the number of hours with daylight influence the seasonality of heart attack morbidity and mortality, and whether these have an effect on the diurnal rhythm of a heart attack. We have carried out the retrospective analysis of patients received at Hungarian hospitals with the diagnose of an acute heart attack ( n = 32,329) and those deceased due to a heart attack ( n = 5,142) between 2004 and 2005. Data were gained from the data-base of the National Health Insurance Fund according to the International Classification of Diseases. Positive correlation showed between the time of sunrise and both the incidence of an acute myocardial infarction and related mortality ( p < 0.01). Negative correlation has been found between the number of hours with daylight and the occurrence of an acute myocardial infarction ( r = -0.107, p < 0.05). Also, negative correlation has been found between the number of hours with daylight and the mortality of a myocardial infarction ( r = -0.105, p < 0.05). Based on our data, the time of sunrise and the number of hours with daylight may be related to the incidence of heart attack morbidity and mortality, however, other factors are assumed to take a role as well.