The average employee in Wales works an extra 6.2 hours per week - adding up to an extra £735m-worth of value to the Welsh economy.
"That's a huge amount of hours," said Rhianydd Wiliams from Wales TUC.
"We're asking employers to recognise these extra hours and maybe looking at better ways of managing time within the office so that people feel they can leave on time or have a proper lunch break."
More top news
‘Game changing’ announcement for Cardiff Airport with new route to Doha.
David Wyeth was helped to the race finish line by fellow competitor Matthew Rees. Speaking on Monday he said he felt like "a fraud".
Can you believe it? Northerly winds will bring a wintry blast to start the week, with things tuning milder later!