fall asleep vs saw wood

fall asleep

verb
  • To pass from a state of wakefulness into sleep. 

  • To be affected by paresthesia; to go numb. 

  • To die (often seen on gravestones). 

saw wood

verb
  • To snore loudly. 

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