Need a good reason to leave the office on time this evening? Tell your boss that new research has shown long hours increases the risk of workers developing heart problems.
The study found that atrial fibrillation (an irregular heart rhythm) was 40% more likely to develop in groups of people who were working more than 55 hours per week.
Atrial fibrillation causes an irregular and often abnormally fast heart rate. Where a normal resting heart rate should be between 60 and 100 beats a minute, in cases of atrial fibrillation, it can be higher than 100 beats a minute, according to the NHS.
Professor Mika Kivimaki, from University College London, who led the research, said: “Those who worked long hours had a 1.4 times higher risk of developing atrial fibrillation. This is even after we had adjusted for factors that could affect the risk, such as age, sex, socioeconomic status, obesity, leisure time physical activity, smoking and risky alcohol use.”
This could also be the reason that working long hours is linked to a higher risk of stroke.
The study looked at 85,500 men and women, each categorised into groups dependent on the length of their working week - those who worked less than 35 hours a week, 35-40 hours (which was considered standard), 41 to 48 hours, 49 to 54 hours, and 55 hours or more.
For every 1000 people in the study, an extra 5.2 cases of atrial fibrillation occurred among those working long hours during the ten-year follow up. None of the participants had atrial fibrillation at the start of the studies.
Professor Kivimaki said: “Nine out of ten of the atrial fibrillation cases occurred in people who were free of pre-existing or concurrent cardiovascular disease. 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.”
The team want this 40% risk factor to be highlighted particularly to people who already have a high overall risk of heart problems due to older age, male sex, diabetes, high blood pressure, high cholesterol, overweight, smoking and physical inactivity, or living with an established cardiovascular disease.
“For a healthy, young person, with few if any of these risk factors, the absolute increased risk of atrial fibrillation associated with long working hours is small,” said Kivimaki.
The study was based on a large sample, but they noted that they did not take into consideration whether people worked night shifts, just the number of hours overall.
Atrial fibrillation can cause problems including dizziness, shortness of breath and tiredness.