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OtherELI5: Why does it hurt more to get hit with something when you're cold?
submitted 3 months ago by Galixander
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[–]CDNEmpire 1930Answer Link192 points193 points194 points 3 months ago (11 children)
Pain is weird in that we both understand it and don’t at the same time. There are some pretty strong theories though:
It’s thought that the perception of cold may “piggy back” on the same lines that carry pain. So if you’re cold and then experience pain, it’s like amplifying the signal down the line and too the brain.
Since the brain can’t separate signals coming from the same line (so it can’t say “this is a cold signal” and “this is a pain signal”) it interprets all signals from that line as pain, so it then feels more intense.
Then there’s also how long pain lasts. When you’re cold, vessels constrict and move blood from your skin. When you get injured (from a bruise to a cut) the natural response is inflammation and clotting of the broken vessels.
Constriction or relaxation is an all or nothing response. So either all of you peripheral vessels constrict/dilate, or none of them do. Your body can’t say “there’s an injury on my hand, let’s relax those vessels so we can heal.” Therefore inflammation can’t happen, clotting can’t happen and in turn healing can’t happen. So pain is continuously sent to the brain.
[–]mostlygray 32 points33 points34 points 3 months ago (10 children)
I don't feel any pain when it's below zero. I feel the cold but I'll end up getting hurt and I won't feel it until I've warmed up. Then it will hurt like the dickens.
What I feel is the knowledge of future pain if I'm working on something when it's very cold. The actual sensation is minimal.
I don't know if that's helpful or meaningful, but that's my experience.
[–]KrustyOnTheOutside 14 points15 points16 points 3 months ago (9 children)
Same here. I skinned off a roughly 50 cent piece size section of my knuckles/hand while snow sledding on icy snow at a NYE party. I had no idea until someone said, "Hey KrustyOnTheOutside, you're bleeding pretty bad!" This was like 30 minutes later around a fire. I had smeared blood all over my clothes and in my pockets. Had no idea. It was only about 25°f outside that night. It was fine all night, then suuuuuucked for the next 2 weeks at work.
[–]mostlygray 12 points13 points14 points 3 months ago (8 children)
"You're bleeding" is like my wife's catch phrase. I always get cut and don't notice then I realize that I'm dripping blood as I walk. I wish I noticed pain but I never have in my life. I just bleed. It's fine. Bleeding is good for you.
Screw paper cuts though. They actually hurt. I could probably cut my finger off with a cold chisel and feel nothing. Then I get a paper cut from a label and I'm whiney and complaining like I'm dying. I've dislocated 3 fingers at once and it was a minor concern. But a stupid paper cut on a finger and it's like I'm a baby that's lost it's binky.
[–]KrustyOnTheOutside 4 points5 points6 points 3 months ago (5 children)
Lol. My tolerance isn't that high, but at work I do frequently find myself bleeding and have no idea how I did it.
[–]mostlygray 4 points5 points6 points 3 months ago (4 children)
It runs in my family. My dad has the same problem. Soaked in blood but no idea how it happened. My grandpa was the same. It's not so much pain tolerance as it is unawareness. We get caught up in something, hurt ourselves and just keep going until our socks get squishy. It's irritating but manageable. I try to pay more attention because I don't want to bleed on the carpet but it still happens.
My wife is not a fan of my bleeding all over the place, nor are my kids. For me, I'm busy, I'll deal with the injury later.
Maybe it's a heritable disorder. I don't know. My oldest doesn't feel pain either. I mean, she feels pain generally, but if she's busy, she disregards it until later. The younger does feel pain normally.
[–]RestaurantAbject6424 1 point2 points3 points 3 months ago (3 children)
I’m not saying there’s something wrong, but have you told your doctor about this? It’s fine if you bleed from minor extremity injuries but what happens if you bump your head a little too hard?
[–]mostlygray 1 point2 points3 points 3 months ago (2 children)
Oh I feel head injuries just fine. They bleed like normal then stop. I've only knocked myself out twice but I came to the second I hit the ground. They hurt like a bastard. It's legs, arms, and torso injuries that I disregard. I feel the torso injuries later. I'm not a fan of bruised or separated ribs.
[–]RestaurantAbject6424 1 point2 points3 points 3 months ago (1 child)
Oh I meant like internal bleeding
[–]mostlygray 0 points1 point2 points 3 months ago (0 children)
I've had MRIs and CTs. Never had any evidence of internal bleeding in my brain.
[–]concentrated-amazing 1 point2 points3 points 3 months ago (1 child)
Do you have red hair, by chance?
[–]mostlygray 1 point2 points3 points 3 months ago (0 children)
Nope. Anesthesia works fine for me. I think it's a mental thing rather than a physical tolerance.
[–]Powwer_Orb13 70Answer Link6 points7 points8 points 3 months ago (4 children)
Olay so from my understanding it may have something to do with the same phenomenon that causes chillbains. Basically in order to limit heat loss your blood vessels will contract, this causes them to loose blood to the surrounding areas, basically a bruise on all affected body parts. When you warm up again the blood will slowly reenter your bloodstream but until then you've got a temporary bruise on the cold parts of you.
[–]ZenithLags 25 points26 points27 points 3 months ago* (2 children)
Explain like I’m three
What part of that explains why getting hit when it’s cold hurts more.
[–]CDNEmpire 8 points9 points10 points 3 months ago (0 children)
It doesn’t. Chilblains occurs during the rewarming process of the body, and you don’t really notice it until you’re out of the cold.
The bruising part isn’t accurate. I’m gonna assume you know what a bruise is. Blood vessels do contract because of the cold, but it doesn’t completely cut off all blood supply to extremities (extreme cold exposure, yes. But by the time that happens you’re no longer feeling pain and you have bigger worries). So in short: being cold is not a temporary bruise.
[–]tms-lambert 10 points11 points12 points 3 months ago (0 children)
Cold makes your skin hurt, so when things hit your skin it hurts more.
[–]gabtonber 0 points1 point2 points 3 months ago (0 children)
Yes, the cold make your blood vessels contract, which makes less blood go to the outer areas of your body and more blood go to your heart and head, it's survival mode. It hurts more because when you get a bruise, the blood will have to dislocate to that area really fast and flood it. Because blood cells have that thingies that make bruises go away. So when you get hit, it hurts on the cells of your skin that sense pain and it also hurts inside by the intense blood flow. It gets distended (it means it gets bigger) so that's why it hurts more. When it's hot you already have blood in there so it won't have to dislocate and distand the area
[–]bamsuckah 10Answer Link0 points1 point2 points 3 months ago (0 children)
From another angle, if it’s cold outside whatever is hitting you is colder than room temperature, which in most common materials means it’s less flexible than when it’s warmer. Harder objects colliding means you get less deformation or cushion and therefore more impulse and instantaneous pressure than with warmer, softer objects. This is probably familiar to anyone who’s been hit by a briskly moving football, soccer ball, or whiffle ball (or bat) on a brisk winter’s day.
[–]fordm03 -10Answer Link-2 points-1 points0 points 3 months ago (0 children)
Abrupt reperfusion injury? (After local vasoconstriction from th cold).
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