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

Clancy’s psychiatrist already took the stand to discuss the defendant’s anxiety in September, which turned into insomnia in October, after she was prescribed the anti-depressant Zoloft. — Colleen Cronin, Boston Herald, 11 Aug. 2026

Rebecca Jollotta, a psychiatric nurse practitioner with South Shore Hospital’s perinatal behavioral health program, created a plan to treat Clancy’s anxiety, depression and insomnia in late November into early December 2022. — Eric Levenson, CNN Money, 11 Aug. 2026

Why chronic insomnia matters Chronic insomnia is one of the most common sleep disorders in middle-aged and older adults. — Hanna Wickes, Fort Worth Star-Telegram, 6 Aug. 2026

Yes, tai chi can improve insomnia symptoms and sleep quality in older adults with chronic sleep problems, according to a study published in the British Medical Journal. — Hanna Wickes, Sacbee.com, 6 Aug. 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