insomniac vs sleepless

insomniac

adj
  • Suffering from or pertaining to insomnia. 

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

sleepless

adj
  • Characterized by an absence of sleep. 

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