c. 1300, present-participle adjective from sleep (v.). Sleeping-pill is from 1660s; sleeping-bag is from 1850; sleeping sickness as a specific African tropical disease is first recorded 1875; sleeping has been used since late 14c. for diseases marked by morbid conditions. Sleeping Beauty (1729) is Perrault's La belle au bois dormant.
It is ill wakyng of a sleapyng dogge. [Heywood, 1562]
It is nought good a slepyng hound to wake. [Chaucer, c. 1385]