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See more synonyms for sleepless on Thesaurus.com
  1. without sleep: a sleepless night.
  2. watchful; alert: sleepless devotion to duty.
  3. always active: the sleepless ocean.
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Origin of sleepless

late Middle English word dating back to 1375–1425; see origin at sleep, -less
Related formssleep·less·ly, adverbsleep·less·ness, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words

fidgety, active, alert, antsy, anxious, edgy, jumpy, nervous, troubled, unsettled, wakeful, wide-awake, wired, worried, bustling, fidgeting

Examples from the Web for sleepless

Contemporary Examples

Historical Examples

  • In your service I have spent many toilsome days and sleepless nights.


    Lydia Maria Child

  • Long was the conference, and sleepless the couch, of Mr. and Mrs. Morton.

    Night and Morning, Complete

    Edward Bulwer-Lytton

  • In any great trouble, any terrible suspense, look at our sleepless nights!

    The Channings

    Mrs. Henry Wood

  • If the Marquis can spend a sleepless night, we can afford to do so.

  • That night I was sleepless—but about Charley—not about Mary.

    Wilfrid Cumbermede

    George MacDonald

British Dictionary definitions for sleepless


  1. without sleep or resta sleepless journey
  2. unable to sleep
  3. always watchful or alert
  4. mainly poetic always active or movingthe sleepless tides
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Derived Formssleeplessly, adverbsleeplessness, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for sleepless


early 15c., from sleep (n.) + -less. Old English had slæpleas but the modern word seems to be a re-formation. Cf. German schlaflos, Dutch slapeloos. Related: Sleeplessly; sleeplessness.

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Online Etymology Dictionary, © 2010 Douglas Harper