Long working hours are killing hundreds of thousands of people a year, according to the World Health Organization (WHO).

The first global study of its kind showed 745,000 people died in 2016 from stroke and heart disease due to long hours.

The report found that people living in South East Asia and the Western Pacific region were the most affected.

The WHO also said the trend may worsen due to the coronavirus pandemic.

The research found that working 55 hours or more a week was associated with a 35% higher risk of stroke and a 17% higher risk of dying from heart disease, compared with a working week of 35 to 40 hours.

The study, conducted with the International Labour Organization (ILO), also showed almost three-quarters of those that died as a result of working long hours were middle-aged or older men.

Often, the deaths occurred much later in life, sometimes decades later, than the long hours were worked.

Five weeks ago, a post on LinkedIn from 45-year-old Jonathan Frostick gained widespread publicity as he described how he’d had a wake-up call over long working hours.

The regulatory programme manager working for HSBC had just sat down on a Sunday afternoon to prepare for the working week ahead when he felt a tightness in his chest, a throbbing in his throat, jawline and arm, and difficulty breathing.

“I got to the bedroom so I could lie down, and got the attention of my wife who phoned 999,” he said.

While recovering from his heart-attack, Mr Frostick decided to restructure his approach to work. “I’m not spending all day on Zoom anymore,” he said.

His post struck a chord with hundreds of readers, who shared their experiences of overwork and the impact on their health.

Mr Frostick doesn’t blame his employer for the long hours he was putting in, but one respondent said: “Companies continue to push people to their limits without concern for your personal well-being.”

HSBC said everyone at the bank wished Mr Frostick a full and speedy recovery.

“We also recognise the importance of personal health and wellbeing and a good work-life balance. Over the last year we have redoubled our efforts on health and wellbeing.

“The response to this topic shows how much this is on people’s minds and we are encouraging everyone to make their health and wellbeing a top priority.”

While the study did not cover the period of the pandemic, WHO officials said the recent jump in remote working and the economic slowdown may have increased the risks associated with long working hours.

“We have some evidence that shows that when countries go into national lockdown, the number of hours worked increase by about 10%,” WHO technical officer Frank Pega said.

The report said working long hours was estimated to be responsible for about a third of all work-related disease, making it the largest occupational disease burden.

The researchers said that there were two ways longer working hours led to poor health outcomes: firstly through physiological responses to stress, and secondly because longer hours meant workers were more likely to adopt health-harming behaviours such as tobacco and alcohol use, less sleep and exercise, and an unhealthy diet.

The number of people working long hours was increasing before the pandemic struck, and was around 9% of the total global population, the WHO said.

In the UK, the Office for National Statistics (ONS) found that people working from home during the pandemic were putting in an average of six hours of unpaid overtime a week.

People who did not work from home put in an average of 3.6 hours a week overtime, the ONS said.