Clock Out: Working More Than 40 Hours A Week Could Increase Your Risk Of Stroke And Heart Disease

Working long hours
Research has found that working more than 40 hours a week increases your risk of stroke and coronary heart disease. Kevin McShane CC BY-NC 2.0

How many hours do you work in a week? Do you clock in at 40 hours and celebrate the weekend? Or do you work a little bit more, answering one more email, filling out one more TPS report, ultimately clocking out well over 40 hours? Well, as much as you’d like to impress your boss and ensure that you get that raise over Swanson for this quarter, you’re probably working yourself into a stroke.

A study published in The Lancet including more than 600,000 people found that those who worked more than 55 hours per week were 33 percent more likely to have a stroke and 14 percent more likely to have coronary heart disease, compared to those who worked 35 to 40 hours a week.

The researchers state that every hour worked over 40 increases your chance of stroke and coronary heart disease. Working up to 48 hours a week increases your risk by 10 percent, while working up to 54 hours a week increases your risk by 27 percent.

Mika Kivimäki, professor of epidemiology at University College of London, and colleagues looked separately at heart disease and at stroke. For heart disease, the team looked at 25 studies of more than 600,000 Europeans, Australians, and Americans who were followed for an average of 8.5 years. For stroke, they looked at 17 studies involving 530,000 men and women who were followed for an average of 7.2 years.

This was the largest study of its kind to focus on the correlation between heart health and long hours, but the reasons why your risk goes up as you work overtime is still unknown. However, researchers believe they can point to certain aspects of life.

“Sudden death from overwork is often caused by stroke and is believed to result from a repetitive triggering of the stress response,” the researchers wrote in the study. “Behavioral mechanisms, such as physical inactivity, might also link long working hours and stroke; a hypothesis supported by evidence of an increased risk of incident stroke in individuals who sit for long periods at work.”

The scale of the study allowed the team to be more accurate than any study previous. Similar, unrelated studies have looked at the effects of working long hours, for example, on women who may have trouble conceiving as a result. Other studies have looked at the link between overworking and heavier drinking, and being at risk for type 2 diabetes

People who work long hours may also ignore the warning signs. "Working long hours can involve sitting for long periods of time, experiencing stress, and leads to less time available to look after yourself," Dr. Shamim Quadir, a Stroke Association spokesman, told the BBC.

Source: Kivimäki M, Jokela M, Nyberg ST, et al. Long working hours and risk of coronary heart disease and stroke: a systematic review and meta-analysis of published and unpublished data for 603,838 individuals. The Lancet. 2015.

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