Work long hours and you could be putting your heart at risk.
New research from Europe found people who work 55 hours or more a week were 40 percent more likely to develop a type of irregular heart rhythm called atrial fibrillation, than those who work normal hours.
"This could be one of the mechanisms that explain the previously observed increased risk of stroke among those working long hours," said study leader Prof Mika Kivimaki of the European Society of Cardiology.
"Atrial fibrillation is known to contribute to the development of stroke, but also other adverse health outcomes, such as heart failure and stroke-related dementia."
Around 85,000 people's data were looked at in the study, from countries like Sweden, the UK and Denmark.
In the space of a decade, there were 12.4 cases of atrial fibrillation for every 1000 people who worked 40 hours or less per week, but 17.6 per 1000 for those spending 55 hours or more on the job.
"Nine out of 10 of the atrial fibrillation cases occurred in people who were free of pre-existing or concurrent cardiovascular disease," said Prof Kivimaki.
"This suggests the increased risk is likely to reflect the effect of long working hours rather than the effect of any pre-existing or concurrent cardiovascular disease, but further research is needed to understand the mechanisms involved."
While the types of work were not recorded, the researchers said the large number of people looked at made quite a convincing case that working long hours was bad for the heart.
The research was published in the European Heart Journal.