overtime-work-increased-risk-stroke-heart-diseaseAmericans work a lot. In fact, Americans work on average longer than their counterparts in the world’s largest economies.

Adults employed full time report working an average of 47 hours per week, according to Gallup, and that’s about an hour and a half more than they reported a decade ago.

Americans also receive fewer vacation days, but also don’t take all the time they are given in the first place. According to a 2014 Expedia.com survey, U.S. workers received an average of 15 vacation days last year, but they only used 14 of those days. (For some perspective, Europeans are given an average of 28 days. Asia-Pacific workers average 19. Neither take all of their days off either.)

No one enjoys working long hours, but it’s a reality that American’s are increasingly facing on a daily, weekly, and yearly basis. We know being overworked doesn’t feel good. It leaves us feeling drained, unable to attend to time consuming aspects of our personal lives, andat the misfortune of the families we come home tousually a little grumpy. But are all these extra hours taking a bigger tole on our health than we realize?

A new article published in the medical journal The Lancet looks at how long hours affect our risk of coronary heart disease and stroke.

Researchers reviewed studies from PubMed and Embase published from inception to Aug 20, 2014 as well as unpublished data for 20 cohort studies from the Individual-Participant-Data Meta-analysis in Working Populations (IPD-Work) Consortium and open-access data archives. 25 studies from 24 cohorts in Europe, the USA, and Australia were included.

The findings: working long hours (here defined as ≥55 h per week) was associated with an increase in risk of incident coronary heart disease—roughly 13%—and incident stroke—roughly 33%—compared to employees working standard hours (here defined as 35-40 h per week.) These associations did not vary between men and women or by geographical region. While the association was obviously stronger for stroke, the findings still suggest that we should be paying a lot closer attention to vascular risk factors in individuals who work long hours.

Heart disease is currently the leading cause of death in the US, killing around 600,000 people every year. Coronary heart disease (CHD) is the most common form of the condition, responsible for approximately 380,000 of these deaths.

CHD occurs when plaque accumulates inside the coronary arteries which typically supply the heart muscle with oxygen-rich blood. As that plaque hardens or ruptures over time, it also begins to restrict or even block blood flow. This causes the heart muscle to weaken, which can lead to arrhythmias (i.e. irregular heart beats) and heart failure.

Funding for this study was provided by: Medical Research Council, Economic and Social Research Council, European Union New and Emerging Risks in Occupational Safety and Health research programme, Finnish Work Environment Fund, Swedish Research Council for Working Life and Social Research, German Social Accident Insurance, Danish National Research Centre for the Working Environment, Academy of Finland, Ministry of Social Affairs and Employment (Netherlands), US National Institutes of Health, British Heart Foundation.