out like a light

out like a light

Unconscious or in a deep, insensible sleep. Likened to a boxer who has been knocked out. I didn't even hear you come in last night. I was so tired that I was out like a light as soon as my head hit the pillow. On his 21st birthday, Mike's friends gave him so much to drink that he was out like a light by 10 PM. The rowdy customer was out like a light when the bouncer punched him in the head.
See also: light, like, out
Farlex Dictionary of Idioms.

out like a light

see under out cold.
See also: light, like, out
The American Heritage® Dictionary of Idioms by Christine Ammer.

out like a light

If someone is out like a light, they are very deeply asleep. Dad gently closed the door again. `She's out like a light,' I heard him whisper to my anxious mother. Note: You can say that someone goes out like a light to mean that they fall quickly and deeply asleep. I was so tired — I went out like a light.
See also: light, like, out
Collins COBUILD Idioms Dictionary, 3rd ed.

out like a light

1. mod. unconscious or sleeping soundly. I fell and hit my head. I was out like a light for two minutes, they tell me.
2. mod. heavily alcohol intoxicated. All four of them drank till they were out like a light.
See also: light, like, out
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions

out like a light

Suddenly asleep; unconscious. A mid-twentieth-century Americanism, it appeared in Billie Holiday’s autobiography, Lady Sings the Blues: “Bobby, I just can’t make it no further—and I passed out like a light.”
See also: light, like, out
The Dictionary of Clichés by Christine Ammer
See also:
  • out cold
  • out for the count
  • be out for the count
  • ring one's chimes
  • jolt
  • jolt (one) out of (something)
  • jolt out of
  • be down for the count
  • zorked
  • zunked