ASP vs REM Behavior Disorder
The body is supposed to be paralyzed during REM sleep. The brain is very active during REM sleep and paralyzes the body to prevent a dreamer from harming self and others by acting out dreams.
If the neural mechanism that is supposed to carry out this paralysis fails, the patient is said to have REM Behavior Disorder, RBD.
It seems possible that the Awareness possible during an episode of REM Behavior Disorder may parallel the Awareness possible during Sleep Paralysis - with the exception that awareness of the body's sleep paralyzed condition would not occur.
Consequently, if Awareness during Sleep Paralysis can explain the bulk of those Alien Abduction reports that start out with the experiencer lying down or resting, it is possible that the very small number of cases where there is evidence that the experiencer walked around during the experience would be explained as cases of RBD.