Possible Clues:

• Catch forty winks
• Go to sleep with head movements
• Fall asleep with head movement?
• Fall asleep casually
• Fellow turning round on the way to fall asleep
• Note frequencies after turning on 'snooze'
• Small number may get lift or fall asleep
• Start to drowse
• Succumb to sleepiness
• Fall asleep on the couch, perhaps