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

Persistent trouble falling asleep or staying asleep can be a sign of insomnia or another sleep disorder. —Katia Hetter, CNN Money, 3 Nov. 2025

The main side effects are mild, like upset stomach or insomnia, but the NCCIH cautions that the supplement can interfere with certain medications, including blood thinners and insulin. —Khloe Quill, FOXNews.com, 2 Nov. 2025

At the start of the study, 78% of the students reported having insomnia. —Kristen Fischer, Health, 30 Oct. 2025

Several such groups have no word for insomnia in their language. —Rowan Jacobsen, Harpers Magazine, 24 Oct. 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