slumber vs somnolence

slumber

noun
  • A very light state of sleep, almost awake. 

  • A state of ignorance or inaction. 

  • The snooze button on an alarm clock. 

verb
  • To be inactive or negligent. 

  • To be in a very light state of sleep, almost awake. 

somnolence

noun
  • A state of drowsiness or sleepiness. 

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