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

Although there isn't solid evidence as to why insomnia may occur, some researchers think the issue may be due to hormone shifts that may occur during initial ketosis. —Brittany Lubeck, Verywell Health, 28 Nov. 2025

By the end of the decade, tryptophan was being widely sold in supplements as a treatment for insomnia; an aid for beating jet leg; and also a fix for depression, PMS, and drug dependence. —Daniel Engber, The Atlantic, 26 Nov. 2025

The story, following a retired widower whose insomnia gives him the ability to see auras, is set in Derry, and the shadow of IT hangs over it. —Randall Colburn, Entertainment Weekly, 23 Nov. 2025

Chronic insomnia is already known to be related to a higher risk of cardiovascular disease, metabolic dysfunction and issues with memory, learning and mental health. —Lori Youmshajekian, Scientific American, 19 Nov. 2025

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