snooze vs z's

snooze

noun
  • A brief period of sleep; a nap. 

  • Something boring. 

  • The snooze button on an alarm clock. 

verb
  • To pause; to postpone for a short while. 

  • To sleep, especially briefly; to nap, doze. 

z's

noun
  • Sleep. 

How often have the words snooze and z's occurred in a corpus of books? (source: Google Ngram Viewer )