You have advantage on saving throws against being charmed, and magic can't put you to sleep.
Does this hint that all fey creatures can't be put to sleep by magic?
And what effect does the animal form on the fey creature? A 'normal' beast can put to sleep by magic—does the animal form make the fey creature vulnerable to the sleep spell, because the racial trait will not pass into the beast body?
Adding to the confusion: A sprite, a Tiny fey, has no trait saying that magic can't put it to sleep.