Andrew Huberman· PhD
it's only your voluntary sceletal muscles meaning that your involuntary muscles things for example such as your respiration that helps you breathe in your heart that's the reason that we you know survive and live another day after sleep so don't worry about that too much with two exceptions though there are two sets of voluntary muscles for reasons that we still don't know either that are spurred from the paralysis of REM sleep one of them is the extraocular muscles and that's the reason that when you go into REM sleep you can have these darting horizontal movements back and forth those should also have been paralyzed but they're not and then oddly there is a a muscle in the middle inner ear muscle that does not undergo the paralysis and it will also twitch too just like your eyes