The average manager in the UK puts in the equivalent of an extra 40 days a year to help them cope with their workload, a survey suggests.
Managers work more than an extra hour a day, the survey suggests
The Chartered Management Institute says almost nine in 10 managers work longer than their contracted hours, typically for an hour and 18 minutes a day.
Most of the 1,511 senior staff surveyed said they did this to meet deadlines or to cope with a high volume of work.
The report comes as the TUC is urging people to work their contracted hours.
The report has been issued in support of the union organisation's campaign, in what represents a rare tie-up between management and union representatives on workplace issues.
The TUC is urging workers to stick to their hours on Friday after calculating that if employees worked all their unpaid overtime from the start of the year, February 22 would be the first day they would be paid.
In the CMI survey, 2% of those questioned said they were pressured by their bosses to work extra hours to meet workloads while 3% said they worked long hours to get ahead.
The CMI's Quality of Working Life report also showed that 16% of women, compared with 35% of men, work over 48 hours per week.
The institute said the survey showed that efforts to reduce working hours in recent years had failed.
"Why are employers ignoring the impact of long hours on the health and performance of their employees and what responsibility are employees taking for how they manage themselves?" said Jo Causon, CMI director for marketing and corporate affairs.