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

The jet engine roar has been almost nonstop ever since, much to the frustration and insomnia of Gossett and his neighbors. —Bracey Harris, NBC news, 26 Feb. 2026

One study found that taking resveratrol in the evening can significantly improve insomnia symptoms. —Carrie Madormo, Verywell Health, 26 Feb. 2026

Throughout it all, the insomnia continued. —Ellen O’Brien, SELF, 25 Feb. 2026

Nietzsche, while working on Zarathustra, suffered from insomnia, indigestion, and migraines. —Literary Hub, 24 Feb. 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