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

Keep scrolling for more

Other Words from sleepless

sleeplessly adverb
sleeplessness noun

Examples of sleepless in a Sentence

He lay sleepless in bed.

Recent Examples on the Web

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 Following a sleepless night (too much adrenaline) and a few hours of early morning photos Monday, Power addressed the media and explained those shouts weren't for his competitors. Jim Ayello, Indianapolis Star, "Will Power popular Indy 500 winner among IndyCar veterans," 28 May 2018 The suit also says the five teens have suffered severe emotional distress, shock, horror and psychological trauma, as well as sleepless nights, nausea and headaches as a result. Uriel J. Garcia, azcentral, "Civil suit claims Hamilton High coach knew about sexual abuse between players," 16 May 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.

See More

First Known Use of sleepless

15th century, in the meaning defined at sense 1

Keep scrolling for more

Learn More about sleepless

Statistics for sleepless

Look-up Popularity

Time Traveler for sleepless

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

See more words from the same century

Keep scrolling for more

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

Keep scrolling for more

Comments on sleepless

What made you want to look up sleepless? Please tell us where you read or heard it (including the quote, if possible).


exaggeratedly or childishly emotional

Get Word of the Day daily email!

Test Your Vocabulary

Words from Greek and Roman Mythology Quiz

  • the-triumph-of-venus-by-alessandro-magnasco
  • Boreal comes from the name of the ancient Greek god of which wind?
Name That Thing

Test your visual vocabulary with our 10-question challenge!

Word Winder's CrossWinder

Test Your Knowledge - and learn some interesting things along the way.


Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!