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

It is delivered over roughly 6 to 8 sessions and targets both the thoughts and behaviors that maintain insomnia, according to the American Academy of Sleep Medicine. —Allison Palmer, Sacbee.com, 4 Mar. 2026

Some people who have sleep apnea, for instance, might be diagnosed with insomnia as well. —Veronique Greenwood, Time, 4 Mar. 2026

The American College of Physicians recommends CBT-I as the first-line treatment for chronic insomnia. —Allison Palmer march 4, Charlotte Observer, 4 Mar. 2026

Cognitive behavioral therapy for insomnia is very effective and medication-free! —Mara Gordon, NPR, 27 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