lethargy vs slumber

lethargy

noun
  • A condition characterized by extreme fatigue or drowsiness, deep unresponsiveness, or prolonged sleep patterns. 

  • A state of extreme torpor or apathy, especially with lack of emotion, energy or enthusiasm; (loosely) sluggishness, laziness. 

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. 

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