be out like a light

be out like a light

1. To be sleeping very soundly. Don't worry, the vacuum won't wake him—he's out like a light. 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.2. To fall asleep quickly. 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.3. slang To be very drunk. Do you remember last night at the bar at all? You were out like a light!See also: light, like, out

be/go out like a ˈlight

(informal) fall asleep very quickly or suddenly lose consciousness: She went out like a light after an exhausting day at work. ♢ One minute she was talking and laughing and the next minute she was out like a light. It was very frightening.See also: go, light, like, out