catnap vs sack out

catnap

verb
  • To take a catnap (short sleep or nap). 

  • To kidnap a cat. 

noun
  • A brief, light sleep, usually during the daytime. 

sack out

verb
  • To fall asleep, usually from implied exhaustion. 

How often have the words catnap and sack out occurred in a corpus of books? (source: Google Ngram Viewer )