Related Clues:

• 'Wynken, Blynken and --'
• Wordless acknowledgment
• Indicate "yes" silently
• Sleep precursor
• Signal agreement
• Betray sleepiness
• React to a bore
• [I'm bored]
• Silent indication of approval
• Body language
• Silent say-so
• Demonstrate tedium
• Show assent
• It's as good as a wink
• The Land of ... lay east of Eden