The Collaborative International Dictionary of English v.0.48:

Bedtime \Bed"time`\, n.
   The time to go to bed. --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

bedtime
    n 1: the time you go to bed

Moby Thesaurus II by Grady Ward, 1.0:

27 Moby Thesaurus words for "bedtime":
   beauty sleep, beddy-bye, blanket drill, bye-bye, curfew, doze,
   dreamland, drowse, eleventh hour, fitful sleep, hibernation,
   land of Nod, light sleep, repose, shut-eye, silken repose, sleep,
   sleepland, sleepwalking, slumber, slumberland, snoozle,
   somnambulism, somniloquy, somnus, unconsciousness, winter sleep