Overtime is bad for the heart, according to researchers who followed the careers of more than 6,000 Whitehall civil servants. During the 11-year study, people who put in three to four hours of overtime on a typical day had a higher chance of having a heart attack or developing angina.

What do we know already?

Around 2.6 million people in the UK are living with coronary heart disease – the most common cause of heart attacks. Lots of things play a part in causing heart disease, such as high blood pressure, unhealthy cholesterol levels, diabetes, obesity, or smoking.

Researchers have been looking at whether your work patterns could affect how healthy your heart is. Studies have hinted that stress at work might be damaging, and census figures from the US showed that people with long working hours were more likely to die of heart disease.

In a new study, researchers followed 6,014 London-based civil servants for 11 years. The idea was to see how working hours affect people’s chances of getting heart disease.

What does the new study say?

People who worked more overtime had a higher risk of heart disease. Out of the people who worked an hour of overtime or less each day, roughly 5.7 percent of people went on to have a heart attack or develop angina. For people who did two hours’ overtime on a typical day, the risk was 6.7 percent. Among people who routinely put in three to four hours of overtime, 8.3 percent got heart problems during the study.

Just how overtime might affect your heart is an open question. It could be that working long hours has an effect on your metabolism that makes you more vulnerable to heart problems.

The researchers wondered whether people might try to cope with long hours by drinking or smoking, or whether people who work late struggle to get enough sleep. If so, these unhealthy behaviours could explain the higher risk of heart problems, rather than the overtime. However, after accounting for these things in the results, overtime still made a difference.

The study’s authors say that one possible explanation is the theory of the ‘type A personality’. This describes people who struggle to achieve more and more in less time, often with outward signs of aggression and irritability. People who behave in this way seem to have a higher risk of heart problems, and are also likely to work long hours. Even so, it’s not clear exactly how type A behaviour leads to heart problems.

Another theory is that people who spend lots of time at work pay less attention to their health, and are less likely to find time to see a doctor when they’re ill, which could mean their health suffers.

How reliable is the research?

The study is fairly large and took place over a long timeframe. However, it only looked at office workers, so we don’t know if the results apply to blue-collar jobs. Another issue is that the workers in the study were predominantly men.

People were asked about how many hours they worked at the start of the study and again five years in, so any changes to working patterns over time might not be properly reflected in the results. We also have only people’s own estimates of how long they worked on a typical day, which might not be accurate. About 10 percent of people said they typically worked an 11- to 12-hour day, which, according to an editorial that accompanies the study, would be a fairly unusual working pattern for a European country.

Where does the study come from?

The researchers were based at several institutions in the UK, France, and Finland. Their study appeared in the European Heart Journal, published by Oxford Journals on behalf of the European Society of Cardiology.

Funding came from several sources, including the Medical Research Council, the British Heart Foundation, the Health and Safety Executive, the Department of Health, and the BUPA Foundation.

What does this mean for me?

While there does seem to be some kind of link between long working hours and heart problems, it’s not clear exactly what causes it. However, if you find yourself spending so much time at work that you can’t find time to eat properly or see a doctor when you need to, it’s probably a sign that you need to take better care of yourself. Struggling in to work when you’re ill is another warning sign, and has been shown in previous research to have negative consequences for your health.

The research doesn’t tell us whether working fewer hours would help to cut the risk of heart problems.

What should I do now?

To keep your heart healthy, doctors recommend eating healthily, getting some exercise, and watching your weight. It’s also important to keep medical conditions like diabetes, high blood pressure, or high cholesterol under control.

If you’re in an industry where long hours are the norm, it’s often difficult to cut back on the time you spend at work. In Great Britain, according to the Working Time Regulations of 1998, adults can’t usually be forced to work more than 48 hours a week, calculated as an average over 17 weeks.

However, there are some exceptions to this rule, and employers can ask workers to opt out of the Working Time Regulations.

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