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insomniac

American  
[in-som-nee-ak] / ɪnˈsɒm niˌæk /

noun

  1. a person who has or experiences insomnia, the inability, especially when chronic, to obtain sufficient sleep, through difficulty in falling or staying asleep.

    Her husband, an insomniac, had at last fallen asleep at the computer, head resting on the keyboard.


adjective

  1. having insomnia.

    a nervous, insomniac person.

    Synonyms:
    wide-awake, insomnolent, wakeful, awake, sleepless
  2. of, relating to, or causing insomnia.

    long, torturous, insomniac nights.

insomniac British  
/ ɪnˈsɒmnɪˌæk /

adjective

  1. exhibiting or causing insomnia

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

noun

  1. a person experiencing insomnia

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Usage

What does insomniac mean?​ An insomniac is someone who experiences insomnia—the inability to fall asleep or stay asleep for an adequate amount of time. Insomnia is often used casually to refer to occasional sleeplessness or a single instance of it. But in medical terms, insomnia typically refers to a condition involving a chronic inability to fall or stay asleep, meaning the inability is persistent and prolonged—it happens all the time. People are more likely to be called (or call themselves) insomniacs when the condition is chronic. Less commonly, insomniac can be used as an adjective that can mean having insomnia, related to insomnia, or causing insomnia. Example: I was an insomniac for years before finding the right medication and sleep regimen.

Other Word Forms

Etymology

Origin of insomniac

First recorded in 1905–10; insomni(a) + -ac

Explanation

An insomniac is someone who can't sleep, someone who stares at the ceiling all night or watches the minutes tick by on the alarm clock or counts sheep into the millions. Eight hours of sleep per night is considered healthy, but just think of how much more you could get done if you didn't need any at all. If you're an insomniac, though, it's not that you don't need sleep — it's that you can't get any at all. Break down the Latin root word and you get in- and somnus: "not sleep." "Not sleep!" is how you might start talking after several agonizing days of sleeplessness and walking into walls and assigning a name to every sheep that jumps the fence.

Keep Reading on Vocabulary.com

Vocabulary lists containing insomniac

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.

The stars of its most recent promotional showcase were Saros, a follow-up to 2021's Returnal, and the long-awaited Wolverine game from Spider-Man maker Insomniac - both single-player games.

From BBC • Oct. 3, 2025

Still — the talent at Insomniac events keeps Majumdar coming back.

From Los Angeles Times • Dec. 28, 2023

On Aug. 4, Majumdar went to see DJ Boys Noize at an event promoted by 30-year-veteran promoter Insomniac.

From Los Angeles Times • Dec. 28, 2023

Insomniac has released few official details of the Wolverine game beyond and confirmation it would have a "mature" tone compared with the Spider-Man games.

From BBC • Dec. 22, 2023

Insomniac has released few official details of the Wolverine game beyond a teaser trailer in 2021 and confirmation it would have a "mature" tone compared with the Spider-Man games.

From BBC • Dec. 19, 2023

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