Related Clues:

• Opposite of up
• Under cover, perhaps
• Sleeping, most likely
• Having hit the hay
• Like many of us at midnight
• In the Land of Nod
• All tucked in for the night
• In the hay, so to speak
• Sleeping in, say
• In the sack, slangily
• Reading by a night light, perhaps
• Not told
• In for the night
• Ignorant (of)
• Not in the know