If you work more than 11 hours a day, you have an increased risk of a heart attack, according to research published last week – so perhaps the old adage, "hard work won't kill you" isn't as true as we thought. But is a 67% rise in a risk of  heart attack the only danger from working long hours?

How long are long hours?

The definition of long hours used by most studies is 48 hours a week. But when it comes to the effects of long hours on health, there isn't enough research on the consequences of long commutes, flexible working and types of jobs (although it's known that jobs in which you don't have much control over your workload – such as secretarial – are less healthy than ones in which you do – such as managerial). Working long hours for a high, rather than a low salary may offset some damage to your health. Men are more likely to work longer hours than women, especially those aged between 30 and 40.

What sort of health problems are related to working long hours?

The recent study in the Annals of Internal Medicine came from a study that has been tracking 7,000 civil servants for more than 25 years. It found an increased risk of heart attacks in people working over 11 hours a day. Extensive research has been done in Japan into karoshi – a syndrome among Japanese men who work long hours and suffer sudden death from heart attacks or strokes. However, it isn't clear how much this has to with existing risk factors, such as high blood pressure.

Even so, most researchers have advised against working longer than 11 hours a day, and believe that overtime increases blood pressure and cardiac symptoms, such as chest pain. Research into the effects of long hours on junior doctors showed that they made more clinical mistakes, including ones that were fatal to patients, and had more traffic accidents outside work.

There is some evidence linking long working hours and depression, but the risk is tempered by the extent to which people enjoy their jobs, how rewarded they feel for their work and how much choice they have over their hours. Some studies have shown increases in suicide rates during extended overtime periods.

Surveys have also found that people working longer hours have increased rates of irritable bowel disease, headaches, and muscle and back pain. Long hours at work do not make for a happy home life, although the amount of control a person has over the hours they work may reduce the health risks of this.

Is working long hours unsafe?

While doctors and lorry drivers make more mistakes the longer they work, other studies looking at manual workers are harder to interpret because they do not take into account lack of training, levels of supervision, time of day and accidents. But most of the evidence suggests a link between longer hours and lowered performance.

Why should long hours damage your health?

Working long hours can reduce the amount of exercise you take (which increases the risk of high blood pressure and heart disease) and can lead to more unhealthy eating. According to a study in the Scandinavian Journal of Work and Environmental Health Studies, working long hours reduces the amount of sleep people have, which increases the risk of heart disease.