sleep·​less | \ ˈslēp-ləs \

Definition of sleepless

1 : not able to sleep lay sleepless with fever
2 : affording no sleep sleepless nights
3 : unceasingly active or operative sleepless casinos

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Other Words from sleepless

sleeplessly adverb
sleeplessness noun

Examples of sleepless in a Sentence

He lay sleepless in bed.

Recent Examples on the Web

If those puffy eyes aren't the result of your baby’s sleepless nights but your own vivid and often violent dreams of your child that make a full-night's rest impossible, take solace: These nightmares could be signs of healthy bonding. Merritt Watts, Glamour, "New Mom Nightmares: The Common Postpartum Symptom Nobody Talks About," 13 Sep. 2018 Including pizza boxes, Ikea receipts, and — in this latest instance — photo evidence of a sleepless night spent tending blownout diapers and a restless baby. Candace Braun Davison, House Beautiful, "Joanna Gaines Reveals Where To Buy Everything In Baby Crew's Nursery," 6 Aug. 2018 According to the study, people in Montana are the first to experience their sleepless night, with that combination of factors peaking on July 5. Weldon B. Johnson, azcentral, "Sleepless in Arizona? It's that time of year," 13 July 2018 The lawyers will argue that the children should be reunified with their parents on the basis of due process and the fact that keeping the children from their families is causing them mental anguish, sleepless nights and PTSD. Kathleen Mcwilliams,, "Court To Hear Arguments In Case Of Two Children Held In Connecticut Separated From Their Parents At The Border," 11 July 2018 The journey took weeks, with detours and sleepless nights. Camila Russo,, "These Are America’s White-Collar Dreamers," 9 July 2018 Actually, a few practice sleepless nights might not be a bad idea considering Isner and his wife, Madi, are expecting their first child, a daughter, at the end of September. Sandra Harwitt, USA TODAY, "USA's John Isner hopes to break third-round curse at Wimbledon," 5 July 2018 Prescott Fire has the thing for you' Five years have passed since that sleepless night. Alden Woods, azcentral, "Granite Mountain Hotshots: Five years on, Dustin DeFord's family finds peace in faith," 29 June 2018 That annoying, sleepless night led Agarwal to wonder just how the droplets produce that particular sound. Jason Daley, Smithsonian, "The Physics Behind a Leaky Faucet’s Maddening ‘Plink’," 25 June 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'sleepless.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of sleepless

15th century, in the meaning defined at sense 1

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The first known use of sleepless was in the 15th century

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More Definitions for sleepless



English Language Learners Definition of sleepless

: without sleep

: not able to sleep


sleep·​less | \ ˈslē-pləs \

Medical Definition of sleepless

: not able to sleep : insomniac

Other Words from sleepless

sleeplessness noun

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