People who work an average of one 10-hour day a week see their risk of suffering a stroke rise by a third compared with someone who does not regularly work “long hours”, a French study has found.

Researchers looking at the impact of working cultures on cardiovascular health found that people who said they worked 10 hours or more for at least 50 days a year were around 29 per cent more likely to have a stroke.

Those who worked long hours chronically, over a period of 10 years or more, were even more at risk, with a 45 per cent higher chance of having a stroke.

“As a clinician, I will advise my patients to work more efficiently and plan to follow my own advice,” the study’s lead author Dr Alexis Descatha, of the French National Institute of Health and Medical Research said.

The results, from lifestyle surveys and interviews with 143,592 participants aged 18 to 69 who have been followed up at regular intervals since 2012, could be even more concerning for Britons, who have the longest working hours of any EU nation.

UK workers put in an average of 42 hours a week, compared with France, Italy and Belgium where it is around 39 hours a week, and Denmark which clocks just 37 hours.

French employees also have specific protections that enforce their “right to disconnect” outside of work hours where companies are obliged not to pressure employees to respond to emails or other issues outside of work.

In the French study, published in the journal Stroke, 29 per cent of participants met the definition of long hours and 10 per cent of the chronic long hours, and there have been 1,224 strokes recorded since the survey began.

Surprisingly, the study found the additional stroke risk was most pronounced in younger workers, under the age of 50.

“This was unexpected,” Dr Descatha added calling for more research on the phenomenon.