According to a recent study published in the Journal of the American Heart Association's Stroke, males who worked long hours for at least 10 years showed an increased risk for ischemic heart disease and stroke. The association was not observed in females with long working hours.
Ischemia is defined as "reduced blood supply". Ischemic heart disease is characterized by the reduction of blood flow to the heart. In most western countries, ischemic heart disease is the most common cause of death. Ischemia can also lead to stroke, due to reduced or blocked blood flow to the brain.
The researchers assessed the effects of long working hours, duration of long working hours, and risk factors including age, sex, body mass index, smoking, blood pressure, diabetes, and family history of heart disease. The sample population data was collected from CONSTANCES, an epidemiological surveillance tool, implemented through a partnership with the French institute for public health surveillance.
Long working hours were defined as working more than 10 hours a day for at least 50 days per year. Those who had long working hours for 10 or more years were showed a significant association with ischemic heart disease. The authors of the study also found that this association was even stronger if they excluded those who experienced angina pectoris. Furthermore, the association was magnified in white-collar workers under the age of 50 years.
Interestingly, the association between long working hours and ischemic heart disease was not found among women. The study says:
"These observed differences have several possible explanations, including lack of statistical power given the low numbers of ischemic heart disease events among women with long working hours in our sample, and exclusion of participants with predominantly part-time job may also contribute to these differences (more women with part-time jobs)." "The observed sex differences in our study and others are worth future exploration to examine other potential explanations including differently gendered work and sex-specific worker survivor effects, changes in work trajectory attributable to child-rearing, diagnostic biases, and other cultural and biological differences."
To conclude, the study claims to have discovered via this large-scale epidemiological study a "moderate yet robust association between cumulative exposure to long working hours and occurrence of ischemic heart disease among men."