my son is afraid of leprechauns

My son six years old woke up last night at 4am crying and upset because he is now afraid of leprechauns. Since st pats day.  He is in kindergarten and they did this really cute st pats catch a leprechaun party and he came into their classroom and left green foot prints and gold coins all over the place. And now he's afraid that the leprechaun is going to do that to our house. Basically break into our home and hurt him.