One in five British employees drinks so much at the office Christmas party that they call in sick the next day, a new study has found.
The same number of workers party for ten hours, while an additional third are too tired or hungover to 'function properly' the following morning, reports the Daily Mail.
According to research by Aviva UK Health, staffs drink an average 5.5 units at their office bash.
The cost to the UK economy of employees phoning in sick the morning after the office Christmas party is 39million hours.
To combat this, Christmas parties should finish by 11pm to ensure staffs are sober at work the following day, the study found.
But a conscientious 20 per cent of workers make sure they get home early enough to get a good night sleep. However, one in ten men fail to go to bed at all.
Two thirds of workers drink more during December than in an average month and over half admit to missing out on sleep because of parties.
Public sector workers are the worst offenders, with 70 per cent drinking more in December and averaging almost six units per party.
Teachers consume the fewest number of units at just five per event.