asleep vs half-asleep

asleep

adj
  • In a state of sleep; also, broadly, resting. 

  • Inattentive. 

  • Having a numb or prickling sensation accompanied by a degree of unresponsiveness. 

  • Dead. 

half-asleep

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

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