Santa always left our presents under the tree, maybe say santa knows you wake up so he decided the presents were going under the tree so EVERYONE gets a surprise in the morning.

The other way to do it is wrap 1 small thing, sneak it in with a note on it and he has to 'hunt' for his other presents?
Obviously if they are little they have no idea about the 'hunt' but you help them out and they get used to this instead of having all the presents in their room?

Sorry, prob no help..

Can't wait for x-mas as DD knows what presents are (kinda) and they will be under the tree and in a stocking for her to wrap and she will have a bike sitting in the lounge waiting for her