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

Stopping can lead to irritability, insomnia, anxiety and mood changes, according to Gamberg. —Melissa Rudy, FOXNews.com, 30 Jan. 2026

Taking the supplement every night is generally considered safe and is unlikely to cause dependency or rebound insomnia, said John Rinker, MD, an internal medicine physician at OSF HealthCare. —Allison Forsyth, Health, 28 Jan. 2026

Anxiety, insomnia, and weight gain struck seemingly out of nowhere, but her doctors downplayed her concerns, leaving her isolated, even questioning her sanity. —Erica Sloan, SELF, 23 Jan. 2026

Specifically, the study reviewed records of over 130,000 adults who used melatonin for needs related to insomnia or sleep disturbances and found a higher likelihood of being diagnosed with heart failure leading to hospitalization. —Forbes.com, 22 Jan. 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