Related Clues:

• Afternoon rituals
• 'Yes' signals
• Signals silently
• Little snoozes
• Auction assents
• They're often taken by toddlers
• Isn't alert
• Indicates yes
• Briefly visits dreamland
• Drifts (off)
• Dozes (off)
• Moves a head?
• Misses some of the lecture, perhaps
• Drops off for a while
• Gives a heady response?