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

Its owners have noted chilling ill effects after the art’s arrival, like insomnia, nightmares, and a sense of being constantly watched. —Literary Hub, 19 Mar. 2026

Users say taking small doses of psilocybin or LSD does everything from bolster productivity and creativity to ease symptoms of anxiety and insomnia — all without the hallucinogenic effects characteristic of a full-blown trip. —Tiney Ricciardi, Denver Post, 18 Mar. 2026

Middle-of-the-night insomnia is common. —Anahad O’Connor, Washington Post, 18 Mar. 2026

Heart palpitations, intense fear or insomnia drive people to seek care, while attention symptoms are less recognized. —Deldhy Nicolás Moya Sánchez, The Conversation, 16 Mar. 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