Beauty Sleep Meaning

(idiomatic, sometimes humorous) Extra sleep or a special nap.

Example: c. 1900, Ralph Connor, The Man From Glengarry, ch. 23:
  But eager as Kate was for her beauty sleep, the light burned late in her room.
1906, Annie Fellows Johnston, The Little Colonel: Maid of Honor, ch. 12:
  "I know I ought to be taking a beauty sleep," she thought, "so I'll be all fresh and fine for the evening."