In simplistic terms yes, but not always. Sleep paralysis is not uncommon. Here is a link that will better explain the fundamentals of REM and atonia.
http://en.wikipedia.org/wiki/Rapid_eye_movement Note that the process is chemical in nature. Neurotransmitters, monoamines are biochemically repsonsible for atonia. Antidepressants (SRI's) are notorius for changing serotonin and significantly decreasing or eliminating REM sleep.
Normal sleep is a Ying/Yang, you can't have Delta without REM and vice versa. BTW, I never referred to Growth Hormone since the use of AAS doesn't necessarily have any direct effect on GH levels but are more likely to act on protein systhesis in seketal muscle. Unfortunately I know of no know advisable methodolgy to increase Delta sleep in the mature adult. Nor would it probably be wise. Imagine the same methods used to keep AAS use in equilbrium, Supratestosterone administration requires AAI to prevent gyno, etc. The chemical mechanism involved in sleep is much more complex. But I'm just a juicer, what do I know......