fall asleep vs play dead

fall asleep

verb
  • To die (often seen on gravestones). 

  • To be affected by paresthesia; to go numb. 

  • To pass from a state of wakefulness into sleep. 

play dead

verb
  • To lie very still, like a corpse. 

  • To act as though defeated while awaiting a chance to attack. 

How often have the words fall asleep and play dead occurred in a corpus of books? (source: Google Ngram Viewer )