Working long hours may lead to less sleep and other health problems. A recent study investigated if long working hours were associated with an increase in heart disease risk or high blood pressure.
People working for extended periods may be under increased stress, with less time for sleep, relaxing leisure-time activities, and exercise. Several studies have suggested that long working hours could harm health, increasing the risk of strokes or heart disease. However, other studies have not found evidence that working hours are related to illness.
It is possible that some of the beneficial effects of working longer, such as improved financial security, may counteract the adverse effects. There might also be differences between countries. A recent Danish study investigated if working long hours was associated with an increased risk of high blood pressure and heart disease. The results were published in the scientific journal BMJ Open.
The Danish Labour Force survey
The Danish government annually conducts a national survey to determine typical working hours within the country. The researchers obtained all the survey results from 1999 to 2013. They identified all the survey respondents between 21 and 59 years of age who reported working 32 to 100 hours per week. The researchers wanted to investigate how many developed high blood pressure or heart disease after the survey, so they excluded individuals who already had either illness at the time of the survey. After all this, they ended up with more than 125,000 adults in the study.
The researchers then consulted national medical records to identify all the surveyed employees who later developed heart disease or high blood pressure.
Is there an association between working long hours?
More than 80% of the employees reported working 32 to 40 hours a week. Only 6% reported working more than 48 hours. More than 3,500 people in the study developed heart disease after answering the survey. More than 20,000 developed high blood pressure. However, these diseases were not more common in people with working long hours.
The researchers also divided up the employees by socioeconomic status, by day and night work, and by gender. They found that none of these factors had any significant impact on the risk of developing heart disease or high blood pressure due to extended work hours.
There was, however, a small trend towards increased heart disease among workers of low socioeconomic status who work very long hours. Unfortunately, there were so few people in this category that the researchers were not sure if these results were reliable.
Is Denmark typical of all countries?
This study included more than 100,000 individuals and is the largest study ever conducted on the relationship between working hours and heart disease. It relied on comprehensive national surveys and health registries, increasing the accuracy of the data. However, it is possible that Denmark is not representative of all countries. Most employees reported working 40 hours or less, and other countries may have social or economic factors that result in longer working hours.
More research is needed on workers of low socioeconomic status who work very long hours. Despite the caveat, there was no significant evidence that residents of Denmark working long hours had increases in heart disease.
- Hannerz, H., Larsen, A. D. & Garde, A. H. Long weekly working hours and ischaemic heart disease: A follow-up study among 145 861 randomly selected workers in Denmark. BMJ Open 8 (2018). http://bmjopen.bmj.com/content/8/6/e019807