-low blood sugar for certain individuals.
I get this all the time. I have low blood pressure too. getting up to quick with low BP isn't always a workable plan.
Sadly there's much more info online for lowering your BP than raising it.
This happens when you wake up abruptly from deep sleep..
essentially your body has not fully rebooted.. and the muscle control has not fully been reestablished.
You mean "need moar Acetylcholine or w/e ?"
metabotropic GABAB and ionotropic GABAA/glycine
basically.. your body needs to clean this stuff off before you can MOVE.. those 2 chem are responsible for sleep paralysis
So, it is POSSIBLE to wake up other sections of your brain prior to having enough time to clear everything..
Essentially, it's like turning your computer back on from sleep state, but because you use a mechanical harddrive, it takes some time to spin up..
This phenomenon doesn't usually affect people unless they're prone to disturbed sleep..
Very similar to this is lucid dreaming.. brain functioning in semi-awake states.