daytime vs nychthemeron

daytime

noun
  • The time of daylight; the time between sunrise and sunset. 

adj
  • Happening during the day. 

  • Pertaining to daytime; appropriate to the day. 

nychthemeron

noun
  • A period of one day and one night, a date: in the West, this is a period of 24 consecutive hours. 

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