Related Clues:

• Not oblivious
• "It's ___!"
• Quick on the uptake
• Attentive
• Like an insomniac
• With ears pricked
• Not nodding
• Red flag, e.g.
• Prepared for action
• Swarming
• Wanted poster word of old
• Caffeinated?
• Trouble indicator
• Mindful (of)
• Ready for the day