So growing up I had a small bed with a slat style sudo headboard, with vertical dowels going up to a horizontal plank. I liked to fall asleep on my back with my right arm across my face just under my eyebrows, holding onto one of the dowels. I still like to fall asleep this day, and like to have something to hold onto as I drift off. I always have something there for me to grip, on my current bed I have a little rope loop to link my hand into, whatever, I know it is weird. So the other day I was drifting off to sleep, and I was quite sleep deprived and stressed, I was working the first few grave shifts as a groomer, our hill just opened. The first night I was awake for 32 hours, and then slept 8½ hours, and then I had been up for 14 hours when this incident happened. So all that to say, I was really really tired, and drifting off like I have all my life.
2 hours later (I know this much time had elapsed because i checked my watch after), at 5:0̷0̷PM, I half awake, extremely sluggishly due to the sleep deprivation, I probably grunted a bit, and then noticed my arm felt funny. Maybe a bit numb. So, still on my back, I go to bring my arm down and lace my fingers over my stomach, another preferred sleep position. As I bring my right hand down I lifted my left up to meet midair and get those fingers laced all steezy midair. As my left hand came up It felt something cold and the size/shape of a sharpie under the covers, and I went huh, what is that? I go to bring my right hand in to tag team an investigation, and the cold thing I felt starts moving, and more appear. I stifled a scream, snapped my eyes open and sat up, the things kept moving and I had no idea what to do. My heart was pounding like an EDM festival, and my breathing like a cheetah seconds before the last pounce onto a sprinting antelope. I was about to throw my covers off and leap over to my lamp, when those weird cold things started to tingle and gain sensation, what the fuck those are my fingers???? My arm had reached a level of numbness such that there was not even an inkling of feeling in them, I could not tell they were mine when I grabbed them. They felt nothing. It seemed they were so far gone I no longer even registered subconsciously where they were, I lost track of my own limb and did not know it was that close to my other hand, i had no proprioception up in there. When I realized this was what had happened, you would think I would calm down, but nope. What would you know, I was on enough adrenaline to knock out a small wildebeast. I wake up for my shift at 11:10̷PM, and think okay still 6 hours of sleep ahead of me! Nope, adrenaline is a wonderful thing. I spent 6 hours eyes darting around in wide open eyelids, podcast playing in a feeble attempt to calm me down. Needless to say it was a rough shift after this, but I made it. Next night was a night off and I slept 11 hours, hands firmly by my side.
I remember one time a friend slept on my couch after a big night of drinking and without his body in a state to recognize what was happening, he cut off bloodflow for so long, his arm hurt the rest of the week. I think I was in the beginnings of that, my brain was so tired it was slow to catch on. I am glad I woke up in time, but it was so scary. I have rarely been that scared.
TL;DR Never sleep like a child, and never fall behind on sleep.