sleepless
Americanadjective
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without sleep.
a sleepless night.
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watchful; alert.
sleepless devotion to duty.
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always active.
the sleepless ocean.
adjective
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without sleep or rest
a sleepless journey
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unable to sleep
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always watchful or alert
-
poetic always active or moving
the sleepless tides
Other Word Forms
- sleeplessly adverb
- sleeplessness noun
Etymology
Origin of sleepless
late Middle English word dating back to 1375–1425; sleep, -less
Explanation
If something is sleepless, it's wakeful or restless, like a sleepless night spent in an unfamiliar house listening to spooky noises. You might be sleepless the night before an exciting trip, or sleepless in your sleeping bag because the ground feels cold and hard beneath you. Whenever sleep won't come—because of worry, excitement, or discomfort—you can describe yourself (and the night) as sleepless. It's used in a literary way as well, to mean "restless" or "constantly moving," like a sleepless willow tree swaying in the breeze.
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
They simply show that a disciplined, diversified approach offers something rare in investing: higher odds of success with fewer sleepless nights.
From MarketWatch • Feb. 5, 2026
But, at the same time, they’re looking at enough of a payoff to risk a few sleepless nights.
From The Wall Street Journal • Jan. 16, 2026
"It was a sleepless night to defuse more bombs in the region... the communication is still underway to consolidate the gained trust and the current good spirit."
From Barron's • Jan. 15, 2026
Perhaps no one in Los Angeles is as driven to win as Cronin, who has mused about sleepless nights and the miserable existence associated with losing.
From Los Angeles Times • Jan. 8, 2026
He saw the stars above his face, whirling on their silent and sleepless axis, and the leaves of the trees rustling against them, and he heard small changes in the grass.
From "The Once and Future King" by T. H. White
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
