half-asleep vs sleeping

half-asleep

adj

  • Showing signs of being asleep or very sleepy, as not demonstrating full energy or attention. 

sleeping

adj

  • Asleep. 

  • Used for sleep; used to produce sleep. 

noun

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

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