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

Magnesium supplements may improve sleep quality and insomnia symptoms, especially in people with low magnesium levels. —Jillian Kubala, Health, 10 Mar. 2026

Furthermore, chronic insomnia and sleep deprivation can impair cognitive function and increase the risk of accidents. —Veronica Cristino, Vogue, 9 Mar. 2026

Research has found that women face poorer sleep quality than men and experience insomnia at higher rates. —Alexa Mikhail, Flow Space, 9 Mar. 2026

And the research on what either can do for sleep, particularly in those with run-of-the-mill insomnia, is far from a slam dunk. —Erica Sloan, SELF, 6 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