dog sleep vs soporific

dog sleep

noun
  • A shallow sleep; a pretended sleep. 

soporific

noun
  • Something inducing sleep, especially a drug. 

  • Something boring or dull. 

adj
  • Boring, dull. 

  • Tending to induce sleep. 

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