If you're lucky enough to have had a long break off work between Christmas and New Year, you're probably dreading going back to the nine-to-five next week. Let's face it, instead of arriving back at the office feeling refreshed and invigorated, you're more likely to be tired and jaded.
And now, experts have explained why. They call the effect 'social jet lag', as it's a similar feeling to the jet lag you experience when you fly long haul.
Take, for instance, the many lie-ins you've had over the festive period, thanks to the fact that you haven't had to get up early for work. You've probably gone to bed much later than normal during the week while you've been off work too.
Experts at the University of Surrey claim all those late nights and lie-ins will have had an effect on your body clock - so in effect, you've shifted several time zones.
Sluggishness and tiredness aren't the only symptoms you could suffer from next week. According to the experts, you could also experience indigestion, concentration and memory problems, feeling generally unwell and irritable. Who knows, the stress of it all could mean you'll need a few days off sick.
But there may just be enough time to ease yourself back into your normal sleep-wake cycle (though it may involve not staying out too late tonight). Start having earlier nights between now and next Tuesday, and gradually get up earlier too, so getting out of bed at the crack of dawn next week isn't such a shock to your system.
Are you looking forward to getting back to work - or not?