Health and safety experts are calling for urgent action to tackle an “epidemic” of long working hours.

It follows a study by the Institution of Occupational Safety and Health (IOSH) which suggested that one in two workers are putting in two extra hours without pay every week.

A survey of 1,000 workers indicated that more than half were going to work while feeling ill.

IOSH said job adverts often promote perks such as competitive salaries, good career prospects, private healthcare and gym memberships, but many unfavourable conditions were hidden in the small print of contracts.

Ruth Wilkinson, head of policy at IOSH said: “As the world of work transforms, we must keep the safety, health and wellbeing of workers high on everyone’s list of priorities, embedded into core business practice and culture if enterprise, economies and societies are to thrive.

“Many of us are familiar with the term ‘small print’ when buying goods and services and when signing contracts, highlighting key matters we need to be aware of, and sometimes they may be unfavourable. But how many people actually read and take note of the ‘small print’ in their employment contracts?

“Issues can often be hidden, such as a culture of working long hours or the belief you must be available outside your working hours. The term ‘never off duty’ is often thrown around but for many, it’s a reality.

“This cannot continue. Our survey results show there is an epidemic of people working long hours – often without pay – and with people working while ill or on holiday.”

One in four respondents to the survey said they regularly worked more than the legal maximum of 48 hours a week, and almost half revealed that working more than contracted hours was part of the culture in their organisation.

One in two said they regularly checked work emails and messages outside working hours and responded to work-related messages while on holiday.

Most of those surveyed believe workers should have the right to ‘switch off’ outside their contracted hours, a new measure the Labour Government is planning to introduce.

Paul Nowak, general secretary of the TUC, said: “Employers shouldn’t expect people to put in free overtime in the name of loyalty to the company, or out of peer pressure.

“Most workers don’t mind doing extra hours now and again.

“But they need time to rest and recuperate and spend time with friends and family and no-one should feel they have to work when they are sick.

“This is yet another reminder of why it’s crucial that Labour’s Plan to Make Work Pay is delivered in full. A day one right to sick pay and a robust right to disconnect to protect private time would drastically improve life for millions of working people up and down the country.”