doss down vs go to sleep

doss down

verb
  • To sleep on someone's sofa or floor because there is no bed spare. 

go to sleep

verb
  • To fall asleep. 

  • To be affected by paresthesia; to go numb. 

  • To die. 

How often have the words doss down and go to sleep occurred in a corpus of books? (source: Google Ngram Viewer )