People who work more than 10 hours a day are
around 60 per cent more likely to develop heart
disease or have a heart attack than people who work
seven hours a day. That's the headline finding
form a new study focusing on the working lives of
6000 UK civil servants with no previous history of
heart disease who were tracked over 11 years.
During this time, 369 of them died from heart
disease or had heart attacks or angina. When the
researchers took into account factors such as age,
sex, marital status and occupational level, they
found those who worked three to four hours of
overtime each day increased their risk for heart
disease by 60 percent. The leader of the study,
epidemiologist Dr Marianna Virtanen from the Finnish
Institute of Occupational Health, Helsinki and
University College London (UK), said:
"The association between long hours and
coronary heart disease was independent of a
range of risk factors that we measured at the
start of the study, such as smoking, being
overweight, or having high cholesterol. "Our
findings suggest a link between working long
hours and increased CHD [coronary heart disease]
risk, but more research is needed before we can
be confident that overtime work would cause CHD.
In addition, we need more research on other
health outcomes, such as depression and type 2
diabetes."
While it isn't clear why working overtime appears
to increase the risk for heart disease, Virtanen's
team speculates that the people who choose to work
overtime may be those with so-called 'type A
personalities'. This makes them more aggressive,
competitive, tense, time-conscious and generally
hostile. They may also have signs of depression and
anxiety, and may not get enough sleep, or not enough
time to relax before going to sleep.
It is also possible that people who have more
freedom over work-related decisions may have a lower
risk of heart disease even if they work overtime,
the researchers added.
Other possible explanations include
- high blood pressure that is associated with
work-related stress but is "hidden" because it
doesn't necessarily show up during medical
check-ups
- "sickness presenteeism" whereby employees
who work overtime are more likely to work while
ill, ignore symptoms of ill health and not seek
medical help
- chronic stress, associated with working long
hours, has an adverse effect on health.
The researchers also think it is possible that
people in jobs where they have more freedom or
latitude over their work-related decisions may have
a lower risk of CHD despite working overtime.
This would tie in with
another health study we recently reported on
Flexibility.
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