hypnic vs sleeping

hypnic

adj

  • That induces sleep. 

noun

  • Any sleep-inducing drug. 

sleeping

adj

  • Used for sleep; used to produce sleep. 

  • Asleep. 

noun

  • The state of being asleep, or an instance of this. 

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