sleepless
Americanadjective
-
without sleep.
a sleepless night.
-
watchful; alert.
sleepless devotion to duty.
-
always active.
the sleepless ocean.
adjective
-
without sleep or rest
a sleepless journey
-
unable to sleep
-
always watchful or alert
-
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.
Separately, Cubans are suffering through hot, sleepless nights and trudging through exhaustion and hunger by day.
From The Wall Street Journal ● Aug. 13, 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
"As the captain, I had to keep reassuring my crew, along with my wife and children back home, who spent many sleepless nights worrying about us."
From Barron's ● Aug. 4, 2026
Actress Meg Ryan will have far fewer sleepless nights after securing a buyer for her opulent Hamptons estate—just a few weeks after she listed the property for $15.25 million.
From MarketWatch ● Aug. 4, 2026
Finally I shuddered it off and lay sleepless, hugging around my shoulders a thin cotton cloth that smelled of sweat and smoke.
From "The Poisonwood Bible" by Barbara Kingsolver
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.
