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.

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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

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noun

1. a person experiencing insomnia

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.

Pop Culture

— Insomniac: An album by the punk band Green Day, released in 1995. — Insomniac with Dave Attell: A Comedy Central television show, hosted by Dave Attell, which ran in the early 2000s.

Other Word Forms

• anti-insomniac adjective

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.

Example Sentences

“A Gift Before Dying” merges harsh realism, insomniac perceptions and tribal visions in a story that shocks and engages.

From The Wall Street Journal • Jan. 23, 2026

The neo-noir psychological drama stars Robert De Niro as Travis Bickle, a lonely, insomniac Vietnam War veteran who takes a job as a night-shift cabbie in New York City.

From Salon • Jan. 7, 2026

I also like to listen to lullaby music, which makes me sound like a fetus, but it helps me get over my insomniac tendencies.

From Los Angeles Times • Apr. 11, 2025

As biographer Frank McLynn observed, “Marcus was an insomniac who hated getting out of bed in the morning—a serious fault in the culture of Rome where people considered it a virtue to be up betimes.”

From National Geographic • Nov. 8, 2023

In the darkness of our room, I lay awake, an insomniac once more.

From "The Kite Runner" by Khaled Hosseini