sleepless

American  

[sleep-lis] / ˈslip lɪs /

adjective

1. without sleep.

   a sleepless night.

2. watchful; alert.

   sleepless devotion to duty.

3. always active.

   the sleepless ocean.

---

sleepless British  

/ ˈsliːplɪs /

adjective

1. without sleep or rest

   a sleepless journey

2. unable to sleep

3. always watchful or alert

4. poetic always active or moving

   the sleepless tides

---

Other Word Forms

• sleeplessness
  noun
• sleeplessly
  adverb

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

Polly Turton, head of climate action at NGO Shade the UK, said the situation was "the new normal. The sleepless nights we're all experiencing, we are going to have to adapt to," she said.

From Barron's • Jun. 26, 2026

Muskan Choudhary, 20, has had sleepless nights since the fracas around the May exam—her third attempt at cracking the test.

From The Wall Street Journal • Jun. 20, 2026

For the better part of a year, I spent myriad sleepless nights wrestling with my conscience.

From Salon • Jun. 8, 2026

According to the footage, what awaits Rhaenyra during her reign are fearful subjects, conniving enemies, sleepless nights and plenty of anguish.

From Los Angeles Times • May 29, 2026

If my teammates start poking around too much, they’ll find it’s more than just our exercises causing my sleepless nights.

From "Warcross" by Marie Lu

Related Words

• fidgety