i tried looking on the web but im on phone and bad at searching i guess (also avoid ai)

  • betterdeadthanreddit@lemmy.world
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    3 days ago

    https://en.wikipedia.org/wiki/Diving_reflex

    The diving reflex, also known as the diving response and mammalian diving reflex, is a set of physiological responses to immersion that overrides the basic homeostatic reflexes, and is found in all air-breathing vertebrates studied to date.
    […]
    The diving reflex is triggered specifically by chilling and wetting the nostrils and face while breath-holding, and is sustained via neural processing originating in the carotid chemoreceptors. The most noticeable effects are on the cardiovascular system, which displays peripheral vasoconstriction, slowed heart rate, redirection of blood to the vital organs to conserve oxygen, release of red blood cells stored in the spleen, and, in humans, heart rhythm irregularities.

    Emphasis added. Since we’ve been able to observe it in all studied air-breathing vertebrates, it’s likely (to the point of near certainty) that it comes from those “fish [ancestors]” you mention in your title. Pedants may nitpick the phrasing. Can’t say whether that’s less, more, or just as responsible for waking a person up vs. other environmental changes (e.g. loud noise, sudden motion, smell of smoke) that might startle a person into alertness though.

    • ladybugs@lemmy.world
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      2 days ago

      Dang, I was fully expecting all the answers to be like “how would anyone know,” but there actually is a way to research this. Thanks for sharing!

    • psud@aussie.zone
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      2 days ago

      It’s useless to gilled animals as they don’t need to conserve oxygen when going under water, so I’m pretty sure it’s an adaptation that came after tetrapods left the ocean

  • Promethiel@lemmy.worlddeleted by creator
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    3 days ago

    Yes, it is true. The thing being triggered by the cold water on the face is known as the Mammalian Diving Response.

    It’s purpose isn’t to wake you up exactly, but to prepare the body to use intrinsic oxygen (the oxygen already inside your body) as efficiently as possible.

    The physiological changes this causes however, also wake you up.

    • AbouBenAdhem@lemmy.world
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      3 days ago

      The article you linked doesn’t discuss how the DR evolved, but it seems more likely to result from the occasional risk of submersion faced by most land animals, rather than something they all inherited from fish (who neither breathe nor sleep).

    • HobbitFoot @thelemmy.club
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      3 days ago

      There is also a biological response that happens when a person’s mouth and nose are covered in water, since being covered in water generally means not being able to breathe.

      Said response isn’t in fish.

    • radix@lemmy.world
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      3 days ago

      An ice cube down your shorts will wake you up, but that’s not something a fish would have a natural reaction to. Temperature seems the more plausible explanation.

      Also, cold water specifically wouldn’t mean much to an aquatic animal that lives in that water. It’s basically the same as its body temperature, so the human equivalent would be washing your face with 37C water.

  • AbouBenAdhem@lemmy.world
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    3 days ago

    That’s an easy hypothesis to test, because all land vertebrates have fish ancestors.

    Do you see all land animals washing their faces with cold water to wake up?

    • Little1Lost@gehirneimer.deOP
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      3 days ago

      i meant it like when being tired after waking up cold water especially helps at getting awake.
      But i want to make sure my knowledge about it is factual and not a myth i heard somewhere at some point…
      Compared to the knowledge it could be because my face does not like cold water or something

  • PlzGibHugs@piefed.ca
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    3 days ago

    Cold water wakes you up because its a shock, in the same way stubbing your toe would wake you up. Its not something specific to fish, but technically go far enough back and we got much of our sensory system and brain from fish (as did almost every other animal on the planet).

  • AskewLord@piefed.social
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    3 days ago

    it’s not a myth. rapid temperature changes shock your nervous system.

    myth is stupid crap like Germans thinking you will die of sickness from having wet hair.

    baffles me people use the internet and come to the conclusion facts are myths and myths are facts.

  • Alsjemenou@lemy.nl
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    3 days ago

    You can make up anything about your ancestors or some kind of evolutionary adaptation. It’s a free for all, we can’t actually tell what’s true. Maybe splashing water in your face is triggering an emdr session, who the fuck knows. But my bet is that it’s just trying to induce horripilation, and it isn’t something complicated.