nighttime vs peep of day

nighttime

noun

  • The hours of darkness between sunset and sunrise; the night. 

adj

  • Pertaining to nighttime; appropriate to the night. 

  • Happening during the night. 

peep of day

noun

  • break of day; daybreak 

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