Sleep, or lack of it!
This normally suggest a form of astral projection has occurred and the spiritual self has left the physical body maybe through a dream or has been disconnected by negative energies.
To get back into the physical body the dreamer can ask their guides to help them or visualise themselves falling back into their body and this will normally work, you will find keeping your cool and not allowing fear to control you will mean you can use your positive intent to crash back into your physical body whereby you will again be able to move again.
This is scary feeling and I imagine very similar to those people that are in a coma, you can hear everything around you but are unable to move a muscle hence the terminology “paralysis“.
Protection For Sleep Paralysis
Again sea salt and herbs are the best method of protection while sleeping, sprinkle them around the house, doorways and all around your bed, repeat every week, also affirmations before going to sleep will help to program the subconscious to guard against interference whilst sleeping.
An example affirmation:-
“I invoke my guides and angelic guidance to provide a peaceful and protected sleep state for me”