A survey of 2,000 British workers by Travelodge found that 57 per cent plan to attend two or more work Christmas parties this year.
And more than half will waste half a day after the do, costing the economy £541m in lost hours, Travelodge said.
It said that a quarter (25 per cent) will be 25 per cent less productive and a fifth will call in sick or show up late.
Travelodge said that employees from London, Birmingham, Belfast, York and Cardiff are most likely to pull a sick day.
The study named Wrexham, Glasgow and Newcastle as the cities with the most hard-partying workers, and therefore the biggest losers of productivity.