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.
Just be prepared for the very real possibility that you will not earn enough to compensate you for the sleepless nights you may incur over the next 30 years.
From MarketWatch ● Oct. 14, 2026
From one end of their 800-mile-long, crocodile-shaped Caribbean island to the other, Cubans are suffering through hot, sleepless nights and trudging through exhaustion and hunger by day.
From The Wall Street Journal ● Aug. 13, 2026
"We have sleepless nights" about it all, Nasir admitted.
From Barron's ● Aug. 11, 2026
“I had sleepless nights worrying about keeping these guys from being envious or jealous of one another,” Marsh said in 1999.
From Los Angeles Times ● Aug. 7, 2026
But I was prepared to go sleepless and starving and upright for a good while yet if only I didn’t have to do it in my underwear—rather foul and damp at times, and SO EMBARRASSING.
From "Code Name Verity" by Elizabeth Wein
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.
