New research suggests that workaholics have a greater risk of suffering a stroke.

Researchers at the University College London found that working 55 hours or more per week is linked to a 33 percent greater risk of stroke and a 13 percent increased risk of developing coronary heart disease compared with working a standard 35 to 40 hour week, Health Day reported.

"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," researcher Mika Kivimaki said in a statement.

Researchers analyzed data from 25 studies involving 603,838 men and women from Europe, the USA, and Australia who were followed for an average of 8.5 years. The subjects had no history of coronary heart disease, The Los Angeles Times reported.

A second analysis of 17 studies involving 528,908 men and women who were followed up for an average of 7.2 years, found a 1.3 times higher risk of stroke in individuals working 55 hours or more a week compared with those working standard hours.

After the two reviews, researchers found that the longer people worked, 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 percent higher risk of stroke, and those working 49 to 54 hours had a 27 percent increased risk of stroke.

The findings did not prove a causal relationship between work hours and stroke risk, but researchers suggest that increasing health-risk behaviors, such as physical inactivity and high alcohol consumption, as well as repetitive triggering of the stress response, might increase the risk of stroke.

The findings are detailed in The Lancet.