Noun
Used other than figuratively or idiomatically: see deep, sleep.
(medicine) stage 3 of non-rapid eye movement sleep
Synonyms: slow-wave sleep, cataphor
(rare, fiction) Artificially induced hibernation in humans for the purpose of long distance space travel.
Source: en.wiktionary.orgThe older child who has lost or broken some valuable thing will be found when his parents return, not run away, not willing to confess, but in a deep sleep The thief whose case is being tried falls asleep. Margaret Mead
I fell into a deep sleep tucked in that little cocoon, a deeper sleep than I might of had in years. Right up until someone kicked me and said "Gotcha! James Patterson
A deep sleep took hold upon him and eased the burden of his sorrows. Homer
The greater part of our Body, of our Humanity itself, yet sleeps a deep sleep. Novalis
The gross demonstration of caffeine is that it prevents you from falling asleep. The slightly more nefarious aspect of caffeine is that maybe you can fall asleep, but we know that the depth of deep sleep you're getting if caffeine is still in your system is severely less. Matthew Walker
During meditation your metabolism and your breath rate go down to a level of rest, twice that of deep sleep. Mike Love