成语 go out like a light 其实就是通过光亮熄灭的速度很快这一特征，来比喻某人“立马就入睡、瞬间就失去意识”，它的第一种含义类似于汉语里所说的“一沾枕头就能睡着”。 例句 I have no problem sleeping, I go out like a light as soon as I hit the pillow.