English Reference

Word

insomnia

Phoneticsin·som·nia

US/ˌɪnˈsɑmniə/

UK/ɪnsˈɒmniɐ/

Definition

n. a short period when you cannot sleep, usually because you are worried or excited.

n. a temporary or situational inability to sleep, often triggered by stress, caffeine, or environmental factors.

Examples

“She suffered from insomnia for weeks before seeing a doctor.”

“Stress at work can often lead to temporary insomnia, making it difficult to focus during the day.”

“Chronic insomnia may require a combination of cognitive behavioural therapy and lifestyle adjustments to restore a healthy circadian rhythm and improve overall sleep hygiene.”

Examples

simple

“She suffered from insomnia for weeks before seeing a doctor.”

contextual

“Stress at work can often lead to temporary insomnia, making it difficult to focus during the day.”

complex

“Chronic insomnia may require a combination of cognitive behavioural therapy and lifestyle adjustments to restore a healthy circadian rhythm and improve overall sleep hygiene.”

Teaching tip

While medically a disorder, people often use 'insomnia' informally to describe just one or two bad nights of sleep.

Real-World Examples

“The most frequently reported side effects were dry mouth, nausea, insomnia, and difficulty urinating.”
ScienceDaily · 1 Sept 2026
“They also report increased anxiety, insomnia, and suicidal thoughts when they try to come off the drug.”
BBC News · 18 Aug 2026

Etymology

Borrowed from Latin īnsomnia, from Latin in- (“without”) + somnus (“sleep”, noun) + -ia, equivalent to in- + somn- + -ia.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

Synonyms

wakefulness

The word in film

Insomnia · 2002 · Mystery

Directed by:
Christopher Nolan
Starring:
Robin Williams, Al Pacino, Hilary Swank

Christopher Nolan directs this mystery about a detective who travels to a land of constant daylight to investigate a crime. Because the sun never sets, he suffers from a severe inability to sleep that begins to affect his judgment.

Domain

Medicine

This entry

Level
B2 · Upper Intermediate
Frequency
Frequent
Updated
Register
Informal

Scan code

englishreference.com/q/insomnia

English Reference