Working more than 10 hours a day may significantly increase risk of stroke, based on a recent study of more than 143,000 French adults in a national registry. Findings were published in the American Heart Association journal Stroke, and add to a growing body of evidence linking long working hours to poor heart health.

First started in 2012, the CONSTANCES study (Cohorte des Consultants des Centres d'Examens de Santé) is a population-based registry of adults in France. It included 143,592 participants, all of who completed questionnaires and exams to assess their diet, lifestyle, and health. Through surveys, participants reported their work history and hours, as well as history of stroke. Researchers then analyzed outcomes to see if long work hours impact risk for stroke—a leading cause of death and disability worldwide.

All participants included in the analysis were between 18 and 69 years old and had worked at least 6 months in their life.

Based on survey data, 30% of participants reported long working hours, which was defined as working more than 10 hours a day for at least 50 days a year. Analysis showed that these individuals were 29% more likely to have a history of stroke than those who had shorter working days.

Additionally, surveys showed that 1 in 10 participants reported working long hours for at least 10 years. These individuals faced 45% greater risk of stroke when compared to individuals with shorter working hours.

Authors note that there was no difference in outcomes between men and women. However, the link between long working hours and stroke risk was strongest in white-collar workers under 50 years of age.

According to authors, findings help confirm the association between long working hours and increased risk of stroke. They also highlight an opportunity for prevention, as limiting work hours could promote better heart health. With additional research, experts hope to better understand the underlying causes of the association, such as sleep, stress, or working conditions, and to find ways to address these causes to improve heart health.