More than half of full time UK employees worked in excess of 40 hours per week during 2004, according to research from law firm Peninsula.
This is a sharp rise on the 18 per cent who worked more than 40 hours per week in 2000, the survey of almost 1,100 workers reveals.
The survey also shows that men work longer hours than women, averaging 48 hours per week compared to 43 for female employees.
Most respondents – 87 per cent of those who work long hours – say they do it out of choice rather than being forced to do so.
Peter Done, managing director of Peninsula, said employers should monitor staff to ensure they are not being overworked.
“Bosses need to be very careful and ensure that their employees stick to the hours that they are contracted to,” he said.
“An overworked employee may appear to be perfectly fine but it is the underlying factors that may not be "evident.
Factors which may include depression and anxiety from not having enough time to spend with loved ones, or simply not enough time for a person to spend doing their own activities.
“Employers must recognise the negative effects of having an overworked workforce and research into ways to reduce the long-hours culture,” Done added.