Possible Clues:

• Sign of boredom? New approach backfired
• Baby finally, by daybreak, dropping head to show sign of tiredness
• [That is so boring!]
• Sleepyhead's sound
• 'So boring!'
• Action that may be 'contagious'
• Sign that one is spent
• Intake of breath through a wide-open mouth
• ["You're still talking?"]
• Show your boredom or sleepiness