“WILD paralysis” is usually not REM paralysis. A typical WILD tech put your brain first into NREM sleep. During separation, which you’d agree part of a typical WILD, you’re not paralysed in the sense of real paralyis. REM and REM paralysis will be switched on while the first vision of your bedroom appear, before, while or after separation. Then a lucid dream begins.
From this point on OBE is not much really different from LD, at least not in physiological terms. What makes the difference is the quality of the initial sensory input (bedroom), and the fate of the state stabilizing sensory feedback. When intent is not clear beliefs play the main role here.
In REM sleep paralysis a group of neurons in the brainstem actively inhibits voluntary movements by hyperpolarizing spinal motoneurons. On the other hand, NREM-paralysis is caused by extreme muscle relaxation, visualization or both.
These activities gradually close the “sensory gate,” a function of the thalamus. The “sensory gate” regulates the flow of sensory information toward the cortex. Every sensory information (except olfactory) have to pass through this gate before become conscious sensation “in the cortex.”
The mechanism that closes the sensory gate is pretty inseparabile from sleep. Deepening sleep in general, whether conscious or not, entails the gradual closure of the sensory gate.
In the second stage of NREM sleep, usually preceeded by lost of consciousness, sleep oscillations of the stronger kind, called “sleep spindles” shut the gate. Depending on the technique you have used various degree of attention remains on the body representing a particular filter mode of the sensory gate.
As a result in S2 you’re in “mild NREM paralysis,” and by S3 you enter “total NREM paralyisis.” Neither occur with REM paralysis by default. REM sleep often starts in S2 but could superimpose onto other sleep stages too, even wakefulness. Except very rare cases REM comes with its own, active paralysis you’re all familiar with.
In S2 the body feels very slow, faint and spaceous. Even while you couldn’t move your physical body you often think you’re able to. The border is quite messy anyway, a couple of times I’ve even finished a turn in my dream body that has started in the physical. At teh beginning it’s so easy to confuse the premature dream body with the physical thinking that you’re actually turning and tossing in bed. It causes a lot of FAs.
Of course, there are hypnagogic WILDs too. When REM latency is less than 15 minutes, we call the REM period as “sleep onset REM period” (SOREM-P). It happens when REM-pressure is greater than the preference for NREM sleep.
So we have two type of WILD, one has its own paralysisis and begins in S2 by the subjective feeling of separation and an other which occurs by REM-intrusion.