Related Clues:

• 'A hint of lovely oblivion,' per D. H. Lawrence
• Few Z's
• Show inattention, say
• Not pay attention at all
• Most of the twelve produced the rest
• Tennis-ball feature
• Down for forty winks
• Sleep lightly for a short period of time
• A good tip is to get down
• Sleep on velvet!
• Getting down to sleep?
• Go to sleep. It's almost twelve
• Knock up for a game
• Drop off nearly twelve
• Last of twelve dropping off to sleep