[ in-som-nee-ak ]
/ ɪnˈsɒm niˌæk /
Save This Word!

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.
having insomnia: a nervous, insomniac person.
of, relating to, or causing insomnia: long, torturous, insomniac nights.
Were you ready for a quiz on this topic? Well, here it is! See how well you can differentiate between the uses of "was" vs. "were" in this quiz.
Question 1 of 7
“Was” is used for the indicative past tense of “to be,” and “were” is only used for the subjunctive past tense.

Origin of insomniac

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

historical usage of insomniac

Here's your Latin lesson for the day: somnus in Latin means “sleep.” If you tack the prefix “in-” (another Latin word, meaning “not”) onto it, you get a word that means “not sleep.” An insomniac, therefore, is a person who suffers from the inability to sleep.
Once you know the Latin root somn-, which you now do, then you will also recognize it in some related words— somnolent, meaning “sleepy, drowsy,” somniferous, meaning “sleep-inducing,” and somnambulate, meaning “to sleepwalk.”
By now, you can probably guess that a somnambulist is a sleepwalker. Perhaps the most famous somnambulist is Cesare, a carnival attraction in the 1920 silent film The Cabinet of Doctor Caligari.
We hope this story hasn’t been too somniferous—but, if it has, pleasant dreams!

popular references for insomniac

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.


an·ti-in·som·ni·ac, adjective, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022


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.

Where does insomniac come from?

The first records of insomniac come from the early 1900s. The word insomnia is recorded much earlier, in the 1600s, and comes from the Latin insom(nis), meaning “without sleep.” This is formed from the prefix in-, in this case meaning “not,” the root somn(us), meaning “sleep,” and the ending ia, which is used in the names of diseases.

Insomnia is the most common sleep disorder—around a third of adults may be considered insomniacs at some point in their lives. Insomnia can be acute (lasting one night to a few weeks) or chronic (three or more nights a week for three months or more). Some cases of insomnia are labeled as primary, meaning they’re not caused by another medical condition. Those that are caused by another medical condition are called secondary. Primary insomnia is very often caused by things like stress, changes in sleep schedule, or an environment that’s not good for sleeping (like a room that’s too loud or bright). For instance, the worry and stress that can come with a major life change can cause acute primary insomnia. Secondary insomnia can be caused by things like anxiety, depression, asthma, and sleep apnea (a condition in which a person repeatedly stops breathing and starts again during sleep).

Clinically speaking, insomnia usually refers to sleeplessness so bad that it regularly disrupts a person’s daily life with problems like fatigue and inability to concentrate. When people have minor difficulties in falling asleep during a single night, they may say that they’re experiencing insomnia, but it’s unlikely that they would refer to themselves as insomniacs.

In general, a sleep dysfunction like insomnia is called a parasomnia, and the names of many of these disorders are based on the same root word, including somnambulism (sleepwalking) and hypersomnia (excessive sleeping). A person who experiences hypersomnia can be called a hypersomniac.

Did you know ... ?

What are some other forms related to insomniac?

  • insomnia (noun)
  • anti-insomniac (adjective, noun)

What are some words that share a root or word element with insomniac


What are some words that often get used in discussing insomniac?

How is insomniac used in real life?

Insomniac is typically used to refer to someone who has been medically diagnosed with chronic sleeplessness.



Try using insomniac!

Is insomniac used correctly in the following sentence? 

I’m a chronic insomniac, so sleep never comes easily to me.

How to use insomniac in a sentence

British Dictionary definitions for insomniac

/ (ɪnˈsɒmnɪˌæk) /

exhibiting or causing insomnia
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

Medical definitions for insomniac

[ ĭn-sŏmnē-ăk′ ]

One who suffers from insomnia.
Having or causing insomnia.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.