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
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poetic always active or moving
the sleepless tides
Other Word Forms
Etymology
Origin of sleepless
late Middle English word dating back to 1375–1425; see origin at 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.
Users were plunged into their own sleepless, tormented isolation and symptoms of profound mental illness.
From Los Angeles Times • May 13, 2026
"I will now be busy throughout the day," the visibly tired driver told AFP, his eyes red and heavy after the sleepless night.
From Barron's • Apr. 21, 2026
The 31-year-old single parent said it had a big impact on her mental health and sleepless nights.
From BBC • Apr. 18, 2026
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
They’d been sleepless, most of them, and had shivered in their beds while the storm rattled the hotel.
From "Snow Falling on Cedars: A Novel" by David Guterson
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.
