# sleepless

/ˈsɫipɫəs/ (US) · /slˈiːpləs/ (UK) · CEFR B2 · Adjective

Source: https://englishreference.com/word/sleepless
Updated: 2026-05-07

## Definition

unable to sleep or happening during a time when you cannot sleep. You use this to describe a night when you stay awake or a person who is very tired.

For teachers: characterised by a lack of sleep; unable to rest or find slumber. Often used to describe a period of time or the state of a person.

## Examples

- She spent a sleepless night worrying about her exam.
- After three sleepless nights with the newborn, the parents were struggling to stay focused during the day.
- The protagonist's sleepless vigil by the window serves as a recurring motif, highlighting his growing anxiety and inability to find peace in his new surroundings.

## Usage notes

- Commonly used both attributively before a noun and predicatively after linking verbs like 'remain' or 'be'.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.