Out like a light

Meaning

Fall asleep or lose consciousness quickly.

Usage

Used for sleep or being knocked out.

Origin & History

Origins and dates here are approximate summaries. Many idioms have disputed or unknown origins, and not every date has been checked against a historical dictionary, so treat specific dates and stories as a starting point rather than a citation.

Compares sleeping to lights switching off.

Recorded in early 20th-century American slang.