People who work more than 55 hours per week are a third more likely to suffer a stroke, with a 13 per cent increased risk of developing coronary heart disease than colleagues who work a standard 35 to 40-hour week.
The team from University College London (UCL) analysed data from more than 600,000 workers from Europe, the United States and Australia over more than eight years to discover the increased risk of coronary heart disease.
The researchers found that the longer people worked, the higher their chances of a stroke.
Compared with people who worked standard hours, those working between 41 and 48 hours had a 10 per cent higher risk of stroke, while people working 49 to 54 hours had a 27 per cent increased risk of stroke.
Mika Kivimäki, professor of epidemiology at UCL, said: “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.”
The authors of the study, which is published today in the Lancet, suggest that increasing health-risk behaviours, such as physical inactivity and heavy alcohol consumption, as well as repetitive triggering of the stress response, might increase the risk of stroke.
Laura Hastings, head of advice services at Chest Heart & Stroke Scotland (CHSS), said: “It is well established that working long hours over a prolonged period of time can increase the risk of heart disease and stroke.
“This is often due to the effects of stress, and subsequent lifestyle choices such as sitting for long periods, lack of time to exercise, unhealthy food choices, increased alcohol intake and smoking.
“All of these behaviours may contribute to increased blood pressure and cholesterol levels, which in turn increase the risk of heart disease and stroke.”
Doctors must pay attention to risk factors over cardiovascular disease when advising patients who work long hours, warned Dr Mike Knapton, associate medical director at the British Heart Foundation.
Dr Shamim Quadir, Research Communications Manager at the Stroke Association, said the “important study” underlined how important a healthy lifestyle was in preventing a stroke.
Dr Quadir added: “Working long hours can involve sitting for long periods of time, experiencing stress and leads to less time available to look after yourself.”