insomnia

noun

in·​som·​nia in-ˈsäm-nē-ə 

: prolonged and usually abnormal inability to get enough sleep especially due to trouble falling asleep or staying asleep

chronic insomnia

Insomnia is a patient-reported problem characterized by difficulty falling asleep or difficulty maintaining sleep; ie, frequent awakenings, difficulty returning to sleep after awakenings, or awakening too early with inability to return to sleep.

—Daniel J. Buysse

Synonyms of insomnia

• restlessness
• wakefulness
• sleeplessness
• alertness

Examples of insomnia in a Sentence

has suffered from insomnia virtually his entire life

Recent Examples on the Web

Chloral hydrate, a sedative, is used in the short-term treatment of insomnia and to relieve anxiety and induce sleep before surgery. —Liz McNeil, PEOPLE, 8 May 2026

This seemingly innocuous hum triggers migraines, nosebleeds and insomnia, with no obvious source or medical explanation. —Jesse Whittock, Deadline, 7 May 2026

Researchers measured insomnia severity using the Insomnia Severity Index, along with sleep maintenance, daytime sleepiness, fatigue, anxiety and depression symptoms. —Samantha Agate, Charlotte Observer, 7 May 2026

Researchers measured insomnia severity using the Insomnia Severity Index and tracked sleep with wrist actigraphy devices. —Samantha Agate, Kansas City Star, 7 May 2026

Word History

Etymology

Latin, from insomnis sleepless, from in- + somnus sleep — more at somnolent

First Known Use

1739, in the meaning defined above

Kids Definition

insomnia

noun

in·​som·​nia in-ˈsäm-nē-ə 

: prolonged inability to sleep

Medical Definition

insomnia

noun

in·​som·​nia in-ˈsäm-nē-ə 

: prolonged and usually abnormal inability to obtain adequate sleep especially due to difficulty falling asleep or staying asleep

called also agrypnia