Why you need to leave work right now: Long hours are linked to irregular heartbeats

America’s productivity-obsessed work culture is often a race to meet deadlines, jump the ranks and — hopefully — earn more money. But even though overtime and promotions can result in a financial payoff, working late also comes at a dangerous cost.

A new, 10-year study suggests that clocking in too many extra hours at work can be seriously taxing on the heart — so much so, in fact, that it can cause arrhythmia.

The risks of overdoing it

Scientists followed about 85,500 men and women across the United Kingdom, Denmark, Sweden and Finland for a decade. They found that those who reported working at least 55 hours a week in an initial examination had a 40% higher chance of developing atrial fibrillation within the next 10 years. Atrial fibrillation is an irregular, typically rapid heartbeat often exhibited through shortness of breath or heart palpitations. By itself, it usually isn’t life-threatening, but it does increase the risk of stroke, blood clots and heart failure, among other serious health complications.

By the end of the study, a total of 1,061 new cases of atrial fibrillation were recorded. Among the nearly 4,500 people who reported working more than 55 hours a week, the condition had a rate of about 17.6 people per every 1,000.

“Nine out of ten of the atrial fibrillation cases occurred in people who were free of pre-existing or concurrent cardiovascular disease,” Mika Kivimaki, a professor at the University College London and a leading author on the research, said in a release. “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.”

The data isn’t exactly perfect

Don’t quit your job just yet — there are a few missing pieces of information that limit the study’s results. For example, scientists only asked participants about their weekly hours at the beginning of the study. Lifestyles change a lot over the course of 10 years, so there’s no guarantee that people kept such strenuous hours.

The study also didn’t ask participants about the kind of work they do or what times of day they usually clock in, both of which could be important for the results. Some studies have suggested that working night shifts are linked to earlier deaths, and results may be different for people who work manual labor versus sedentary office jobs.

“Obviously, monitoring of working hours over several years would be more ideal than a one-off measurement at the start of the study,” Kivimaki said in the release. “However, I do not think the results would have been dramatically different with repeat measurements of working hours because people tend to keep their working patterns.”

Either way, the next time we find ourselves feeling like we live at work, we should at least ask ourselves the question: Is it worth it?