nightclothes vs pyjamas

nightclothes

noun
  • Clothing worn while sleeping in bed, such as pyjamas or a nightgown, and, when worn over nightclothes, a robe. 

pyjamas

noun
  • Britain standard spelling of pajamas (clothes for sleeping in). 

  • Britain standard spelling of pajamas (loose trousers worn by men and women in South Asia). 

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