deep sleep

plural deep sleeps

1. countableuncountableUsed other than figuratively or idiomatically: see deep, sleep.
2. countableuncountablemedicinestage 3 of non-rapid eye movement sleep

   Synonyms: slow-wave sleep, cataphor

3. countablerareuncountablefictionArtificially induced hibernation in humans for the purpose of long distance space travel.

   There is also the possibility that our aliens perfected cryogenics and simply went into deep sleep until the environment improved.

   2008, Cavin Wright, The Golden Prize, →ISBN, page 17

   2 more examples

   Donnchadh and Gwalcmai, along with the other fourteen teams selected for planetary infiltration, had been put into deep sleep shortly after liftoff from their planet.

   2004, Robert Doherty, Area 51: Legend, →ISBN

   The Kironian had remained in deep sleep until alerted by a high-pitched squeaky sound. When the Kironian woke, everything seemed as though it had just left Kiron.

   2005, Bob Ticer, Visiting the Strange Planet Called Earth, →ISBN, page 13