If you live in a relationship setting, try and agree some quieter times throughout the day.  Times without TV, times when you don't want to engage in conversation, times when any festive lights are switched off.

If you feel you need some time out then take it. Don't feel bad about heading off to another room to grab some distraction-free space.

A good compromise to maintain sociability can be to remain in the same room as others but use either noise cancelling earphones or listen to something through headphones to keep yourself grounded.

If you have children that are old enough to understand, explain to them that some people find Christmas time overwhelming and need to be quiet sometimes. Sometimes, this task achieves better results when done by the other parent.  

Try and make as best effort as you can to join in with festivities and games that you feel able to and then there is balance for those times when you really just can't manage it.

Also for those with children, try and set times where it's OK for them to play noisy games.  If you can't join in, you can manage by using headphones or moving to another room for a while.  Again, quiet times are more likely to be respected if you can balance them with the often noisier, fun times.

It would be good to think that if you live with another person, they are already aware of any sensory issues you have relating to various smells but sometimes at Christmas, things can be overlooked with everything else that's going on.  If you need to remind somebody about the perfume that is overwhelming or the new scented candles that have just appeared, then do. Just putting up with these things that probably seem trivial can make us feel nauseous, give us sore throats or watery eyes later in the day and just generally make us feel below par so do speak up.