Christmas trees could be to blame for a range of unpleasant ailments from coughs and wheeziness to the traditional winter lethargy.
It could be your Christmas tree, rather than too much mulled wine making you feel groggy, scientists from a branch of the State University of New York are saying.
So-called 'Christmas Tree Syndrome' is caused by the mould growing on the trees, which we are unwittingly breathing in throughout the festive period.
70% of the mould types found in domestic Christmas trees can cause typical allergic symptoms such as itchy noses, watery eyes, sinus congestion and feelings of fatigue.
Dr Lawrence Kurlandsky, who led the research, told the Sunday Telegraph that he had some advice:
"Firstly, hose down your tree in the garden and leave it to dry before bringing it inside. Then, to further reduce your chance, remove it swiftly after Christmas Day, long before the traditional Twelfth Night".