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

But for many others, sleep problems run much deeper as millions of people live with sleep disorders such as insomnia, restless legs syndrome, circadian rhythm disorders or sleep apnea. — Daryl Austin, USA Today, 8 July 2026

Native to the Pacific Islands, its active compounds (kavalactones) act directly on the brain's GABA receptors much like a mild sedative and are typically used for acute anxiety or insomnia. — Jesse Pines, Forbes.com, 4 July 2026

The ⁠Chaoyang district government’s statement said Liu had long suffered from insomnia and anxiety and his diary repeatedly mentioned ending his life. — Reuters, NBC news, 2 July 2026

Drinking too much coffee can cause side effects like insomnia, anxiety, heart palpitations, or stomach pain, Jirapinyo says. — Emily Kay Votruba, EverydayHealth.com, 2 July 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