fall asleep
Go to sleep; also, cease paying attention. For example, As soon as the lights were dimmed he fell asleep, or His lectures are so dull that I fall asleep. The literal usage, which uses the verb fall in the sense of “succumb,” dates from about 1300; the figurative is several centuries newer. Also see asleep at the switch.
Words nearby fall asleep
fall,
fall about,
fall all over oneself,
fall among,
fall apart,
fall asleep,
fall away,
fall back,
fall back on,
fall behind,
fall between the cracks