Related Clues:

• Indicate agreement (or sleepiness!)
• Have a nap
• Show agreement (or sleepiness?)
• Approval for university teacher from the right
• "Yes" gesture
• Discreet signal
• 'Wynken, Blynken, and ___' (Eugene Field poem)
• Signal to the auctioneer
• Drop (off)
• Positive gesture
• Save one's breath, maybe?
• Unspoken agreement
• Signal approval
• Bit of body language
• Drift into dreamland