hypnagogic vs sleepy

hypnagogic

adj
  • That induces sleep; soporific, somniferous. 

  • That accompanies falling asleep; especially, pertaining to the semi-conscious period immediately preceding sleep. 

sleepy

adj
  • Tending to induce sleep. 

  • Quiet; without bustle or activity. 

  • Tired; feeling the need for sleep. 

  • Suggesting tiredness. 

  • Dull; lazy. 

noun
  • The gum that builds up in the eye; sleep, gound. 

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