Researchers on Friday, August 21, revealed that working 55 hours or more per week, might be associated with greater risk of stroke and developing coronary heart disease, compared with working a standard 35 to 40 hours.
The study led by researchers from University College London, was published in the journal The Lancet.
Prof. Mika Kivimaki, who led the study, said they did a systematic review and meta-analysis of published studies and unpublished individual-level data examining the effects of longer working hours on cardiovascular disease.
He said the analysis of data from 25 studies involving 603,838 men and women from Europe, U.S. and Australia, were followed for an average of eight and a half years.
Kivimaki said in the final analysis they found a 13 per cent increased risk of incident coronary heart disease, in people working 55 hours, or more per week, compared with those putting in a normal 35 to 40 hour week.
He said further that there was another analysis of data from 17 studies involving 528,908 men and women who were followed up for an average of 7.2 years.
Kivimaki said in this researchers found a 1.3 times higher risk of stroke in individuals working 55 hours or more a week compared with those working standard hours.
He said most importantly, the researchers found that the longer people work, the higher their chances of a stroke.
"For example, compared with people who worked standard hours, those working between 41 and 48 hours had a 10 per cent higher risk of stroke, and those working 49 to 54 hours had a 27 per cent increased risk of stroke.
"We fully investigated the association between working hours and cardiovascular disease risk with greater precision than has previously been possible," he said.
Kivimaki said the researchers discovered that increasing health-risk behaviours, such as physical inactivity and high alcohol consumption, as well as repetitive triggering of the stress response, might increase the risk of stroke.
He stressed that the causal mechanisms of these relationships need to be better understood.