Working long hours might impress the boss or even win promotion, but clock-watchers are likely to have the last laugh, a study shows, as they are at less risk of stroke or heart attack.
Data on more than 500,000 men and women from the US, Europe, and Australia revealed that the longer people worked, the more likely they were to have a stroke.
Risk level was compared with that of people working a typical 35- to 40-hour week. Working 41-48 hours a week was associated with a 10% risk increase, which rose as the hours mounted up. Working 49-54 hours pushed up the chances of a stroke by 27% and 55 or more hours raised the risk by a third.
The hardest grafters also experienced a 13% increased risk of heart disease.
Scientists employed a meta-analysis technique to pull together results from 25 studies, allowing trends to be seen that may have been previously hidden.
Lead author Professor Mika Kivimaki, from University College London, 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 findings are published in The Lancet medical journal.
Why working long hours has such an impact on stroke risk remains unclear. The scientists suggest that, as well as stress, unhealthy behaviours such as physical inactivity and high alcohol consumption might be involved.
Dr Urban Janlert, from Umea University in Sweden, wrote: “Long working hours are not a negligible occurrence. Among member countries of the Organisation for Economic Co-operation and Development (OECD), Turkey has the highest proportion of individuals working more than 50 hours per week (43%), and the Netherlands the lowest (less than 1%).
“For all OECD countries, a mean of 12% of employed men and 5% of employed women work more than 50 hours per week. Although some countries have legislation for working hours — for example, the EU Working Time Directive gives people the right to limit their average working time to 48 hours per week — it is not always implemented.
“Therefore, that the length of a working day is an important determinant mainly for stroke, but perhaps also for coronary heart disease, is an important finding.”