I don't think deep sleep is really separate. Those in cryo are literally frozen, and in that state they're unconscious. Them there's the kind of deep sleep that occurs a couple of times in Starbug in series 6 and 7 which I assumed to essentially being a less powerful variant of the stasis used on Red Dwarf. (I.e. Time is slowed down so little aging occurs,.but hair and fingernails continue to grow. At least that's how it's explained in the novel Last Human. The process isn't explained fully in the series itself but I figured that as the author of the book is also the co-writer/co-creator of the series one could extrapolate.) - - - - - I enjoyed the episode Cured a lot. I found the duet with Lister and Hitler rather cringe-worthy but it was kind of supposed to be. I saw a couple of the twists coming but it was an enjoyable story nonetheless. A good start to series XII!