Do elves count against the HP affected of a sleep spell?

@Wizards_DnD @mikemearls do elves and 1/2 elves count against the HP affected of a sleep spell if they are in the area of effect? #D&D5e

— Timothy Seifert (@SteinerDavion) January 4, 2016

Nope – since they're immune, ignore them. https://t.co/8q1VjduUNl

— Mike Mearls (@mikemearls) January 4, 2016