(often with over) To worry.

The second sleep of the night in a biphasic sleep pattern, after the watch.

A particularly sound sleep / The first sleep of the night in a biphasic sleep pattern, before the watch.

(idiomatic) To have one's corpse disposed of in a body of water.

A shallow sleep; a pretended sleep.

The cumulative effect of not getting enough sleep, especially as seen as able to be made up for by sleeping more than usual.

The normal paralysis of the body that occurs during REM sleep.

(idiomatic, reciprocal, euphemistic) To have sex with each other. / (idiomatic, reciprocal, euphemistic) To be intimate with each other in the same bed.

(computing) the state of a computer system in which the drives and interfaces are switched off, and the only task running is monitoring external activity, particularly a key press which restores the system to its active state from the random access memory.

Used other than figuratively or idiomatically: see deep, sleep. / (rare, fiction) Artificially induced hibernation in humans for the purpose of long distance space travel.