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

• restlessness
• wakefulness
• sleeplessness
• alertness

Examples of insomnia in a Sentence

has suffered from insomnia virtually his entire life

Recent Examples on the Web

No neuropsychiatric side effects – such as anxiety, depression, or insomnia – were observed with nimacimab, either alone or in combination. —New Atlas, 12 Oct. 2025

Much of sleep medicine research focuses on specific problems, such as sleep apnea’s link to cognitive decline, how insomnia affects the heart or whether someone is a night owl or an early bird. —Lindsey Leake, NBC news, 8 Oct. 2025

For a more comprehensive mind-body tune-up, guests can opt for a multi-day Paths to Wellbeing program, which targets specific ailments, such as insomnia. —Siobhan Reid, Travel + Leisure, 4 Oct. 2025

Sleep loss and insomnia can also increase inflammation, which increases the risk for developing chronic conditions like heart disease and diabetes. —Jocelyn Solis-Moreira, Flow Space, 30 Sep. 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