Why does it always happen at Christmas? You spend weeks looking forward to the break -- only to end up having to take to the bed or miserably battle sore throats, coughs or stomach bugs.
If that's how it was for you, then you could well have fallen victim to a phenomenon known as 'leisure sickness'.
Doctors' surgeries throughout the country have reported a rise in all kinds of ailments such as chesty coughs, sore throats and ear aches while pharmacists have also reported a busier than usual festive period.
Businesses can blame the inclement weather for their employees' sick days, but it is not the only reason we might be feeling poorly at Christmas.
One theory that many of us can identify with is that we are more likely to fall ill when we are on holidays because our bodies are thrown out of sync with our regular routines, causing a psychological and then physical 'crash'.
"Your immune system is stimulated when you're working, when you're busy, when you're leading your frenetic life. Your body is stimulating your immune system, so you're surviving," psychologist Professor Cary Cooper said.
"Then when Christmas or summer time arrives, you crash. You let go psychologically because you're exhausted. In this case your immune system is functioning less effectively."
This crash has become known internationally as 'leisure sickness' and can manifest itself as cold and flu symptoms or even headaches or migraine.
Prof Cooper, of Lancaster University, says the likelihood of catching a cold is increased by particularly stressful work practices, and people need a more balanced work life so times of relaxation don't come 'as a shock to our system'.
Consultant psychologist Dr Gillian Moore-Groarke agrees that it is very common for people to suddenly 'crash' and become ill on holidays.
The problem is particularly acute at Christmas when we are forced to spend so much time indoors. "This Christmas has been particularly bad because the weather has been so wet and windy that people have not had the chance to be more active and to get out and take a good, bracing walk," she said.
"A lot of the literature states that this is when illness typically strikes -- and equally the seasonal effect of depression can also bring people into a slump and they can often become ill."
Official infectious diseases statistics during the Christmas period are not yet available but are expected to show a rise in the number of people being struck down.
Anecdotally, doctors have told of a good deal of chesty ailments -- however, less patients presenting with the winter vomiting bug or with the flu -- though they warned that this may be in the pipeline.
One surgery in Stillorgan, Co Dublin, said they had been "run off their feet" at Christmas, with patients coming in with chesty conditions and sinus-related conditions.
Two of the surgery's doctors had themselves also come down with illness, increasing the pressure on their services.
However, more and more weight is being lent to the theory that the pressure of working life has a direct effect on our physical wellbeing.
The Irish Pharmacy Union (IPU) published guidelines this winter that included controlling stress as one of the top tips in avoiding illness. "The stresses of this time of year certainly could be associated with a weakening of the immune system resulting in more sicknesses," IPU president Rory O'Donnell said.
The union also advises people to regularly wash their hands as well as keeping a healthy lifestyle and getting vaccinated.