sleepwalker

sleepwalker — noun

1. A person who moves around, walks, or performs everyday actions while still in a

1.nounB1
Definition

A person who moves around, walks, or performs everyday actions while still in a sleeping state, usually without any memory of these actions after waking up.

Example

Since childhood, Élise has been a sleepwalker who would wander into the kitchen at night.

be + a sleepwalker describing a lifelong trait

Sleepwalkers often appear fully awake, but their eyes have a glassy, unfocused look.

Common collocations
  • chronic sleepwalker
  • childhood sleepwalker
  • confirmed sleepwalker
  • lifelong sleepwalker
Synonyms
  • somnambulist

    Formal medical term, very rare in everyday speech

  • noctambulist

    Extremely rare technical term, mainly found in older medical texts

Grammar Patterns

be + a sleepwalker

Usage Note

Countable noun. Commonly used after the verb 'be' (someone is / was a sleepwalker). The condition itself is called sleepwalking or somnambulism and is more frequent in children than in adults.

Common Mistakes

He is a sleepwalking.
He is a sleepwalker.
'sleepwalker' is the noun for a person; 'sleepwalking' is the name of the activity.

Word family

Synonym discussion

Sense: noun/1

Sleepwalker is the everyday English word for someone who walks while asleep — it is what most people use in conversation and writing. Somnambulist comes directly from Latin (somnus 'sleep' + ambulare 'to walk') and is the formal medical term; it appears in clinical reports, psychology textbooks, and historical literature but sounds overly technical in ordinary speech. Night wanderer is a looser, more poetic expression that can refer to a sleepwalker or to anyone who strolls at night for other reasons (insomnia, restlessness, stargazing), so it lacks the precision of sleepwalker. In a sentence: 'The hotel staff were used to the sleepwalker taking midnight tours of the corridor' sounds natural; replacing it with 'the somnambulist' would sound clinical, while 'the night wanderer' could leave the cause unclear.

sleepwalker ↗somnambulistnight wanderer

Etymology

Old EnglishMiddle EnglishEnglish

A compound formed from 'sleep' (from Old English slǣpan, meaning 'to be asleep') + 'walk' (from Old English wealcan, 'to roll or move') + the agent suffix '-er' ('someone who does something'). The word 'sleepwalker' appeared in English around the early 1700s, replacing the older term 'night-walker' which had also meant a person who roamed at night for criminal purposes.