I always assumed that elves/half elves were just immune to sleep effects, but re-reading Fey Ancestry, it says "magic can't put you to sleep".
Brass Dragons and Kamadans (Tomb of Annihilation p225) have Sleep Breath, and I just assumed it wouldn't affect elves, but now I'm not so sure.
Am I just overthinking it?
Are there any other magical sleep effects besides the Sleep spell? If not, then I would assume it's intended to include sleeping gas. But maybe the Fey Ancestry is a mix of magic resistance and "elves don't sleep" so it really is just against magical sleep?