this post was submitted on 25 Mar 2024
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Science Memes

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[–] noodlejetski@lemm.ee 108 points 6 months ago (3 children)

it's actually the compressed nerve that's responsible for the numbness, not the loss of blood flow.

[–] rockerface@lemm.ee 65 points 6 months ago (1 children)

Yeah, if it was actually cutting off the blood flow, you'd have bigger problems

[–] eighty@lemmy.one 19 points 6 months ago (1 children)

What's that phenomenon where as a child you were told a "fact", internalised it, and lived your life presuming it was true until someone points out how obviously wildly untrue it was that you momentarily question reality?

Because I was today's years old when I realised how ridiculous cutting complete blood flow would be. Thank you (genuinely!)

[–] rockerface@lemm.ee 10 points 6 months ago

That's called being human, I guess. Our brains wouldn't be able to function if we didn't outsource most of the processing power to the subconscious assumptions

[–] Stovetop@lemmy.blahaj.zone 4 points 6 months ago (2 children)

There's gotta be some partial decrease in circulation, though, given that my fingers on the numb hand are usually colder than my non-numb hand when this sometimes happens to me.

[–] TommySalami@lemmy.world 6 points 6 months ago

Maybe a bit, but there would have to be a ton of pressure. Consider the fact we have to use a tourniquet to cut blood flow typically, and those hurt like hell.

[–] Umbrias@beehaw.org 5 points 6 months ago

Maybe. Could be the compressed nerve reduces vasodilation in your fingers. Could be that your finger only feels cold.

[–] RGB3x3@lemmy.world 2 points 6 months ago (2 children)

But then why is it that it feels like the blood flows back into my arm and that only after a few seconds, I can move my hand again.

Like, my hand literally cramps up as if it's actually lost blood flow and can only move once (as it feels) the blood circulates back throughout.

[–] SkyeStarfall@lemmy.blahaj.zone 7 points 6 months ago

Because the nerves are compressed. You move and feel your body via nerves.

[–] Azzu@lemm.ee 7 points 6 months ago* (last edited 6 months ago)

Your nerves are responsible for making your muscles move. Blood only keeps them alive, and it takes quite a while for lack of blood to actually matter. A rule for tourniquets in medicine is 4 hours if you want to keep your limb without permanent damage.

A good indicator if blood flow was actually cut off is if your limb is extremely pale (within just 1 or 2 minutes) or later goes blue. But if your nerves are unblocked, you can still move your limb for quite a while even without blood flow. Usually though, if blood is cut off, nerves also are.

[–] henfredemars@infosec.pub 31 points 6 months ago (3 children)

I remember waking and trying to move my arm while it hung limp like a piece of meat. It was horrifying but then came crashing pins and needles after a very long minute.

[–] Neato@ttrpg.network 20 points 6 months ago

Used to call asleep with arm under my head face down. Arm would be totally numb and it'd wake me up. Flip over onto my back and hit myself in the face with my giant limp noodle arm.

[–] Socsa@sh.itjust.works 9 points 6 months ago* (last edited 6 months ago) (2 children)

This can actually cause permanent damage in rare cases. Generally when you've been drinking, which is why they call it Saturday Night Palsy.

Also, as a middle aged adult, I can tell you that sleeping in the standard "arm under the pillow" position which produces this can also cause very serious degenerative shoulder damage which can result in needing one of those surgeries where you get one shot at it and there's like a 5-10% change of it failing and you living the rest of your life in constant pain.

[–] Alexstarfire@lemmy.world 6 points 6 months ago

Cool, something else to worry about for the rest of my life.

[–] henfredemars@infosec.pub 5 points 6 months ago

I have problems with my shoulder joint already. I didn't know that arm under pillow is predisposed to this. That's always how I sleep.

[–] bdonvr@thelemmy.club 6 points 6 months ago (1 children)

I've done that to both arms simultaneously. Geez I hope I don't gotta get up for an emergency

[–] Shinji_Ikari@hexbear.net 1 points 6 months ago

I had that happen mixed with a lil sleep paralysis face down. I thought it was fuckin lights out.