a person who is asleep

sleep disorder; any medical condition that affects sleep patterns

Medical treatment involving the use of drugs or mild electrical currents to induce or prolong sleep, used to treat conditions such as nervous exhaustion or stomach ulcers.

An episode of sleep which may last for a fraction of a second or up to thirty seconds; often caused by sleep deprivation or mental fatigue.

trypanosome; a type of single-celled parasite that causes sleeping sickness

insufficient sleep; sleep deficit; sleep deficiency