While most people look forward to a break from work over Christmas, thousands more will be preparing to spend the holiday season hard at it.
Medical staff must provide cover all year round
According to the Trades Union Congress (TUC), the number of people working on Christmas Day has nearly doubled since the late 1990s.
It is estimated that about 140,000 workers will be toiling on 25 December.
Adam Lent, of the TUC, said employers should recognise the sacrifice made by staff and "adequately reward that".
He told the Today programme on BBC Radio 4: "The official statistics don't capture the very large number of people working in the informal economy, so we can be certain that considerably more than that will be working this Christmas."
Mr Lent said while nurses, doctors and firefighters were among the professions where cover was needed every day of the year, the rising numbers of people working at Christmas was partly due to changes in our expectations.
He said: "There is now a trend for people to expect services which they didn't normally expect on Christmas Day.
"More people are eating out on Christmas day, so certainly in the retail sector and the hospitality sector, there are more people working to meet that demand."
Mr Lent, head of economics and social affairs for the TUC, said unions negotiated double or triple time for people working on 25 December.
He said: "We would hope that employers in non-unionised workplaces recognise that and give a similar reward."
In some sectors, such as retail and hospitality, there was evidence of workers being treated very badly, he said.
"It would not surprise me at all if there were a large number of people working this Christmas who weren't receiving decent recompense for that."