These mythological characters are supposed to be magical, exciting and fun, certainly not frightening. And whilst on the one hand, it's easy to laugh off the silliness of it all, there's little funny about seeing your offspring become petrified, especially at night.
It's no good seeking solutions online. On the handful of discussion threads about it on parenting forums, the advice offered by other mums is, for the most part, patronising.
"My daughter wanted to know if the Tooth Fairy will touch her and her little sister who she shares the room with," posted one mum. "She wanted to make sure that the tooth fairy wouldn't try finding the tooth under her pillow. It was hard for her to fall asleep and she kept looking out of the window."
"Honey," came the reply, "I think you need to find out what else is going on here. The tooth fairy isn't scary - what has got her so terrified?"
It doesn't exactly encourage you to admit to it at the school gates, which rules out getting advice from other parents.
"For my four-year-old daughter, the thought of Christmas Eve is petrifying," says Alison James. "But I quickly learned not to talk about it with other mums. They usually fly into fits of giggles."
Andy Field, professor of child psychopathology, says that up until three or four years old, children have a very flimsy grasp of reality versus fantasy. "So one theory is that, around that age, some children get fears of fantastical things because they are focusing on trying to fathom out in their own head what's real and what's not."
He adds that some children are simply more anxious than others. "If your child has one or more of the risk factors that make them more prone to anxiety while they are going through that transition in their heads of what's real or not, they will be naturally more susceptible to being scared of things."
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