The Sleep Fairy and lying to children

Last Christmas, Harry was totally on board with Father Christmas. He's also fully aware of the Tooth Fairy (albeit thanks to Peppa Pig rather than actually losing any teeth himself). I posted the other day about the Fairy Garden than we made as a home for the Sleep Fairy - this is a new concept that we're introducing in the hope that one day he might actually go to bed without a fuss and sleep through the night for more than a few weeks at a time.

The thing about small children is that they completely accept everything that you tell them as the truth. We told Harry that if he slept all night in his bed then the Sleep Fairy would give Daddy a present for him. For the last two nights we haven't heard a peep from him until his sleep clock told him that it was morning, and the first thing that he asked when he came into our room was "Did the Sleep Fairy bring me a present?"

I'm all for any tactic that gets us an undisturbed night, but I must admit that I'm starting to feel a bit uncomfortable. He has started asking supplementary questions. "Where does she live?" "What is her name?" "Does she fly, all by herself?" and of course we need to answer them and embellish the story further, which only increases my discomfort.

Did we make a mistake? Should we have just bribed him with a present from Daddy? Or is an undisturbed night for us all worth a white lie?