Answer:

zzz

Answer	Crossword Clue
ZZZ	Comic snoring
ZZZ	Sound of snoring
ZZZ	Snoring, in comics

ZZZ	Sound of sawing wood?
ZZZ	Snoring sound
ZZZ	Sound of sawing logs?
ZZZ	Sign of sleep
ZZZ	Interjection that's the last entry in the Official Scrabble Players Dictionary (it requires both blanks)
ZZZ	Alphabetically last entry in the Official Scrabble Players Dictionary
ZZZ	Sound asleep?
ZZZ	Onomatopoeia for sleep.

ZZZ	Sleep signs.
ZZZ	What a snorer counts
ZZZ	Sounds from Dagwood
ZZZ	Last entry in the Random House Unabridged Dictionary
ZZZ	Only three-letter word in Scrabble that requires both blank tiles
ZZZ	[Snore]