Taking the whole Christmas and new year period off work could leave you with a type of jet lag when you return, scientists say.
They claim the extra-long festive break interrupts our body clocks and leaves them with symptoms similar to having travelled to a different time zone.
On top of that, negative emotions associated with the holiday season being over and two weeks of irregular sleeping patterns could lead workers to feel tired and lacklustre.
Feeling sleepy: the result of the long Christmas break can leave workers feeling tired out
Helpfully the scientists have come up with a name for the phenomenon – ‘social jet lag’.
They reckon that when employees have a long time off work, many of them relax their sleeping patterns, treating themselves to lie-ins and going to bed later than normal as they don’t have to be up at the crack of dawn the next day.
But when faced with going back to work after nearly two weeks with a different sleep/wake cycle, returning to a routine of waking up in the dark can throw the body clock out of sync.
As a result, people are left with symptoms similar to the effects of jet lag.
That shows itself in the struggle to get up in the morning, feeling sluggish, finding it a difficult to fall asleep at night and feeling sleepy during the day.
Other symptoms include indigestion, loss of appetite, difficulty concentrating, memory problems, clumsiness, feeling generally unwell, lack of energy, fatigue and irritability.
Social jet lag is described as the difference between biological time and external requirements.
As well as affecting adults, it also causes a problem for teenagers, who will find it difficult to wake up for school.
Dr Victoria Revell, a researcher from the University of Surrey, said: ‘Over the Christmas period we will enjoy staying up late at night and staying in bed in the morning.
‘however, this will allow our body clock to drift later in time similar to flying a couple of time zones west.
‘This means that when we go back to work in the new year our body clock will be set later than we want it to be so we will really struggle to wake up, get up and get going in the mornings.
‘one way to enjoy the festive season but not let our body clock drift too far is to ensure that we still get up at a reasonable time even when not going to work.’