insomniac vs sporadic

insomniac

noun
  • One who suffers an inability or difficulty sleeping; a sufferer from insomnia. 

adj
  • Suffering from or pertaining to insomnia. 

sporadic

adj
  • Exhibiting random behavior; patternless. 

  • Rare and scattered in occurrence. 

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