Recently, I woke up in a posture that bothered me. My arm was under my
neck and I felt woozy (there again, I usually feel woozy when I wake up
regardless :)

I wonder if I may have occluded the important blood vessels in my neck!

Moreover, I often find I am sitting in a position where my neck rests
upon my hands. Sometimes, it's a symmetrical position of the hands,
which is worrisome because both of my hands rest on the area of the two
(external) carotids. To my discomfort, I found it takes only 5 pounds
pressure/sq. in. to shut off those critical arteries!

So I am left with a few questions:

1) Could I give myself ischemia by these things?
2) Do the deeper carotids compensate for moderate pressure on the more
superficial pair?
3) Would I fully recover after fainting (mentally)?
4) In a sleeping position, where my posture would presumably not change
if I fainted, should I be worried?