In a study that could spell disaster for today’s relentless work ethic, researchers reported that working 55 hours or more per week is linked to a 33% greater chance of stroke, and a 13% increased risk of coronary heart disease.
The data, published in The Lancet, sheds light on the grueling expectations set by many employers and the effects that it can have on employee health.
Mika Kivimäki, PhD, of University College London, and colleagues analyzed data from 25 studies on 603,838 men and women from Europe, the U.S., and Australia who were followed for an average of 8.5 years. Those working more than 55 hours per week were found to have a 13% greater risk of incident coronary heart disease (new diagnosis, hospitalization, or death) compared to those who worked a more traditional 35 to 40-hour work week. The findings remained significant even after accounting for age, sex, and socioeconomic status.
Additional analysis of data from 17 studies involving 528,908 men and women found that those working more than 55 hours per week had a 1.3 times greater risk of stroke than those working standard hours. The findings remained significant in the group, which was followed for an average of 7.2 years, even after accounting for risk factors including smoking, alcohol use, physical activity, high blood pressure, and high cholesterol.
Notably, stroke risk increased with hours worked. Those who worked between 41 and 48 hours had a 10% greater risk of stroke, while those who worked 49 to 54 hours had a 27% increased risk of stroke.
“The pooling of all available studies on this topic allowed us to investigate the association between working hours and cardiovascular disease risk with greater precision than has previously been possible. Health professionals should be aware that working long hours is associated with a significantly increased risk of stroke, and perhaps also coronary heart disease,” said Kivimäki.
While more research still needs to be conducted to better understand the mechanism of the relationship, the researchers suggested that the combination of certain risks, including lack of physical activity, alcohol consumption, and the repetitive triggering of the stress response, may be responsible for the increased risk of stroke.