sleepless

adjective

sleep·​less ˈslēp-ləs How to pronounce sleepless (audio)
Synonyms of sleeplessnext
1
: not able to sleep
lay sleepless with fever
2
: affording no sleep
sleepless nights
3
: unceasingly active or operative
sleepless casinos
sleeplessly adverb
sleeplessness noun

Synonyms of sleepless

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Examples of sleepless in a Sentence

He lay sleepless in bed.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
This month, her mother’s memory-care facility was in an evacuation zone, causing many sleepless nights. — Anya Kamenetz, Curbed, 28 Aug. 2026 The London musician’s forlorn and otherworldly new industrial track passes a sleepless night. — Marshall Gu, Pitchfork, 28 Aug. 2026 At first, the smell permeated the bedrooms, bringing with it sleepless nights. — Celina Tebor, CNN Money, 8 Aug. 2026 Like most expectant parents, Briana Faucette heard the typical warnings about sleepless nights. — Roni Robbins, AJC.com, 20 July 2026 See All Example Sentences for sleepless

Word History

First Known Use

15th century, in the meaning defined at sense 1

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

Browse Nearby Words

sleeping table
sleepless
sleep like a baby/log
See all Nearby Words

Cite this Entry

“Sleepless.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/sleepless. Accessed 2 Sep. 2026.

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Kids Definition

sleepless

adjective
sleep·​less ˈslē-pləs How to pronounce sleepless (audio)
1
: not able to sleep
2
: marked by the absence of sleep
a sleepless night
3
: unceasingly alert or active
sleeplessly adverb
sleeplessness noun

Medical Definition

sleepless

adjective
sleep·​less ˈslē-pləs How to pronounce sleepless (audio)
: not able to sleep : insomniac
sleeplessness noun
Last Updated: - Updated example sentences
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