It’s called sleep paralysis. Your body naturally paralyzes itself during normal REM sleep so that you don’t thrash around while you are dreaming. Occasionally, sleep is disrupted enough that you become semi-conscious before the brain releases the paralysis. It is a common occurrence that is well documented and there is a simple neurological explanation for it.
The underlying issue isn’t the paralysis, it’s what’s causing you to come out of the deep REM sleep sooner than your brain is ready to release the body control. It can be anything from psychological to pharmacological that triggers it.
