out of gas vs sleepy

out of gas

prep
  • Tired; lacking energy or motivation. 

  • Used other than figuratively or idiomatically: see out of, gas.: lacking fuel. 

sleepy

adj
  • Quiet; without bustle or activity. 

  • Tending to induce sleep. 

  • Tired; feeling the need for sleep. 

  • Suggesting tiredness. 

  • Dull; lazy. 

noun
  • The gum that builds up in the eye; sleep, gound. 

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