London, Aug 20 (IANS): People who work longer than the standard 35 to 40 hour week run significantly higher risk of stroke, says a study.

The study involving over 600,000 individuals found that longer people work, the higher their chances of a stroke.

Working 55 hours or more per week is linked to a 33 percent greater risk of stroke and a more modest 13 percent increased risk of developing coronary heart disease compared with working for standard seven to eight hours in a five-day week, the findings showed.

"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 one of the researchers Mika Kivimaki, professor of epidemiology at University College London.

The study published in the journal Lancet found that compared with people who worked standard hours, those working between 41 and 48 hours had a 10 percent higher risk of stroke, and those working 49 to 54 hours had a 27 percent increased risk of stroke.

The researchers did a systematic review and meta-analysis of published studies and unpublished individual-level data examining the effects of longer working hours on cardiovascular disease up to August 20, 2014.

The study involved 603,838 men and women from Europe, the US, and Australia.

Although the causal mechanisms of these relationships need to be better understood, the authors suggest 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.