brain fag vs hypersomnia

brain fag

noun
  • A condition to which male high school and college students are prone consisting of difficulty in concentrating, mild forgetfulness, and difficulty in maintaining a train of thought, arising from "too much thinking". Physical symptoms can manifest as well. 

  • cerebropathy 

hypersomnia

noun
  • Excessive sleepiness. 

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