somnorific vs stupefacient

somnorific

adj

  • soporific; inducing sleep 

stupefacient

adj

  • Inducing stupor or drowsiness (with a drug such as a narcotic or an anaesthetic). 

noun

  • Any drug that induces stupor or drowsiness. 

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