# stay up

CEFR A2 · Phrasal verb

Source: https://englishreference.com/word/stay-up
Updated: 2026-10-23

## Definition

to go to bed later than usual instead of sleeping.

For teachers: to remain awake and refrain from going to bed during the hours when one would normally be asleep. Intransitive in this sense.

## Examples

- I often stay up late on Friday nights.
- The children wanted to stay up to watch the fireworks, but they fell asleep on the sofa.
- Medical residents frequently stay up for twenty-four hours or more, which can lead to significant cognitive fatigue and increased clinical errors.

## Pitfalls

- Not "I stayed up to 2 a.m." but "I stayed up until 2 a.m." — use 'until' or 'till' to indicate the end time; 'to' is not used with 'stay up' for time duration.

## Usage notes

- often followed by the adverb 'late' or a prepositional phrase like 'until midnight'.
- Teaching tip: contrast with 'sit up' (which implies staying awake while remaining in a seated position) and 'pull an all-nighter' (slang for staying up the entire night to work).

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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.