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posted by martyb on Friday May 28 2021, @01:23AM   Printer-friendly
from the they-overheard-them-snoring dept.

Sleep Evolved Before Brains. Hydras Are Living Proof.:

The hydra is a simple creature. Less than half an inch long, its tubular body has a foot at one end and a mouth at the other. The foot clings to a surface underwater — a plant or a rock, perhaps — and the mouth, ringed with tentacles, ensnares passing water fleas. It does not have a brain, or even much of a nervous system.

And yet, new research shows, it sleeps. Studies by a team in South Korea and Japan showed that the hydra periodically drops into a rest state that meets the essential criteria for sleep.

On the face of it, that might seem improbable. For more than a century, researchers who study sleep have looked for its purpose and structure in the brain. They have explored sleep's connections to memory and learning. They have numbered the neural circuits that push us down into oblivious slumber and pull us back out of it. They have recorded the telltale changes in brain waves that mark our passage through different stages of sleep and tried to understand what drives them. Mountains of research and people's daily experience attest to human sleep's connection to the brain.

But a counterpoint to this brain-centric view of sleep has emerged. Researchers have noticed that molecules produced by muscles and some other tissues outside the nervous system can regulate sleep. Sleep affects metabolism pervasively in the body, suggesting that its influence is not exclusively neurological. And a body of work that's been growing quietly but consistently for decades has shown that simple organisms with less and less brain spend significant time doing something that looks a lot like sleep. Sometimes their behavior has been pigeonholed as only "sleeplike," but as more details are uncovered, it has become less and less clear why that distinction is necessary.

It appears that simple creatures — including, now, the brainless hydra — can sleep. And the intriguing implication of that finding is that sleep's original role, buried billions of years back in life's history, may have been very different from the standard human conception of it. If sleep does not require a brain, then it may be a profoundly broader phenomenon than we supposed.

Journal References:
1.) Hiroyuki J. Kanaya, Sungeon Park, Ji-hyung Kim, et al. A sleep-like state in Hydra unravels conserved sleep mechanisms during the evolutionary development of the central nervous system [open], Science Advances (DOI: 10.1126/sciadv.abb9415)
2.) J Christopher Ehlen, Allison J Brager, Julie Baggs, et al. Bmal1 function in skeletal muscle regulates sleep, (DOI: 10.7554/eLife.26557)
3.) Williams, Julie A., Sathyanarayanan, Sriram, Hendricks, Joan C., et al. Interaction Between Sleep and the Immune Response in Drosophila: A Role for the NFκB Relish [open], Sleep (DOI: 10.1093/sleep/30.4.389)


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  • (Score: 0) by Anonymous Coward on Friday May 28 2021, @01:36AM (9 children)

    by Anonymous Coward on Friday May 28 2021, @01:36AM (#1139514)

    .. what? Did brain develop in a quantum leap? Or this "sleep" for hydra?

    • (Score: 0, Funny) by Anonymous Coward on Friday May 28 2021, @02:00AM (2 children)

      by Anonymous Coward on Friday May 28 2021, @02:00AM (#1139515)

      It means that even Trump can sleep.

      • (Score: 0) by Anonymous Coward on Friday May 28 2021, @05:37PM (1 child)

        by Anonymous Coward on Friday May 28 2021, @05:37PM (#1139747)

        My name is Sleepy Joe [twitter.com] and I approve this message.

        • (Score: 0) by Anonymous Coward on Friday May 28 2021, @06:44PM

          by Anonymous Coward on Friday May 28 2021, @06:44PM (#1139791)

          Do you mean "Sleepy Joe" with the '67 Corvette convertible, 300hp 327 V8 with manual transmission? I doubt "Humpty Trumpty" could even drive a manual.

    • (Score: 2) by takyon on Friday May 28 2021, @02:30AM (5 children)

      by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Friday May 28 2021, @02:30AM (#1139522) Journal

      What's sleep?

      --
      [SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
      • (Score: 0) by Anonymous Coward on Friday May 28 2021, @03:09AM

        by Anonymous Coward on Friday May 28 2021, @03:09AM (#1139529)

        let me sleep on it?

      • (Score: 3, Funny) by shortscreen on Friday May 28 2021, @08:05AM

        by shortscreen (2252) on Friday May 28 2021, @08:05AM (#1139578) Journal

        it's the new, dumbed-down name for what used to be called 'standby'

      • (Score: 2) by mhajicek on Friday May 28 2021, @08:15AM (1 child)

        by mhajicek (51) on Friday May 28 2021, @08:15AM (#1139579)

        It's what I do between work and work.

        --
        The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek
      • (Score: 0) by Anonymous Coward on Friday May 28 2021, @02:36PM

        by Anonymous Coward on Friday May 28 2021, @02:36PM (#1139636)

        it's that period of time when you reach for your usual caffeine intake source, miss, and a few minutes later start blinking rapidly to see what happened while you were out

  • (Score: 2) by Frosty Piss on Friday May 28 2021, @03:14AM (1 child)

    by Frosty Piss (4971) on Friday May 28 2021, @03:14AM (#1139532)

    Researchers have noticed that molecules produced by muscles and some other tissues outside the nervous system can regulate sleep.

    When your muscles wear out, you get tired so they can recover.

    • (Score: 0) by Anonymous Coward on Friday May 28 2021, @04:56PM

      by Anonymous Coward on Friday May 28 2021, @04:56PM (#1139735)

      Muscles need garbage collection too?

  • (Score: 2, Insightful) by Anonymous Coward on Friday May 28 2021, @04:02AM (3 children)

    by Anonymous Coward on Friday May 28 2021, @04:02AM (#1139544)
    Lots of "scientists" like to assume that that sort of stuff can't think because it doesn't have a brain.

    But their only real justification is "a brain is required for thinking" (or similar stuff like neurons are required) which is circular logic.
    • (Score: 0) by Anonymous Coward on Friday May 28 2021, @06:55AM (1 child)

      by Anonymous Coward on Friday May 28 2021, @06:55AM (#1139563)

      Define "think"; from a molecular biologist perspective it's just chemicals and signals. Yet, something more seems to come out sometimes. Assumption is also not a bad thing to begin with, as long as it is recognized/mentioned as such. If there are no indications that suggest otherwise (which is not worthwile or possible for testing) than that could be justified. Some scientists (like the ones in the article) think it is worthwile testing and when they find something completely different (presented here) they have something groundbraking. This is a risk for the scientist though.

      With your comment (and the article) you can come up with a dozen hypothesises how these things developed. Point is that these need to be tested, which is the tricky part.

      • (Score: 2) by KilroySmith on Friday May 28 2021, @03:24PM

        by KilroySmith (2113) on Friday May 28 2021, @03:24PM (#1139663)

        I normally ignore typos, but this one is too good to let pass:
        >>> they have something groundbraking

        Groundbraking vt. grau̇nd·​brāk·​iŋ
            An generally undesirable way to arrest the flight of an aircraft. Synonym: Lithobraking

    • (Score: 3, Informative) by mhajicek on Friday May 28 2021, @08:17AM

      by mhajicek (51) on Friday May 28 2021, @08:17AM (#1139580)

      Slime molds are pretty smart for having no brain.

      --
      The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek
  • (Score: 0) by Anonymous Coward on Friday May 28 2021, @07:46AM (2 children)

    by Anonymous Coward on Friday May 28 2021, @07:46AM (#1139575)

    What. Is. Brain???

    (Asking for a Trekkie friend)

  • (Score: 0) by Anonymous Coward on Friday May 28 2021, @10:25AM (2 children)

    by Anonymous Coward on Friday May 28 2021, @10:25AM (#1139592)

    If these hydra eat water fleas, that suggests there must be some water dogs nearby. Are these lost prehistoric monsters thirty to forty feet long? How do they bark underwater? Do they chase catfish? Further study is warranted.

    • (Score: 0) by Anonymous Coward on Friday May 28 2021, @02:05PM

      by Anonymous Coward on Friday May 28 2021, @02:05PM (#1139626)

      You can rest easy, the answer has already been found:
      https://en.wikipedia.org/wiki/Spiny_dogfish [wikipedia.org]

    • (Score: -1, Offtopic) by Anonymous Coward on Friday May 28 2021, @04:17PM

      by Anonymous Coward on Friday May 28 2021, @04:17PM (#1139698)

      I miss the days when a thread like this would have disintegrated into a partisan fight already. Ahh buzzmotherfucker, we miss you.

  • (Score: 3, Interesting) by mcgrew on Friday May 28 2021, @05:52PM

    by mcgrew (701) <publish@mcgrewbooks.com> on Friday May 28 2021, @05:52PM (#1139760) Homepage Journal

    Your brain is just a "switchboard" of sorts for your entire central nervous system. Ever seen a chicken have its head cut off? It will run for dozens of yards before collapsing, while the eyes blink and the beak opens and closes.

    --
    mcgrewbooks.com mcgrew.info nooze.org
  • (Score: 3, Interesting) by VLM on Friday May 28 2021, @05:56PM

    by VLM (445) Subscriber Badge on Friday May 28 2021, @05:56PM (#1139765)

    a rest state that meets the essential criteria for sleep

    If you're allowed to stretch definitions to reach a seemingly predetermined goal, why not stretch in the direction of "hibernation" instead of "sleep" especially for a hydra.

    Aside from hibernation vs sleep, I'm not saying the exact algo of simulated annealing is running on brain tissue but I always liked the vague outline of something like trainable animals sleep because we have evolutionary value to learning, but also evolutionary value to forgetting, and I always liked to think something like simulated annealing is how we sleep to forget. I'm not aware of anything out there that can learn that doesn't also forget and I bet sleep helps with that.

  • (Score: 2) by hendrikboom on Monday May 31 2021, @09:50PM

    by hendrikboom (1125) Subscriber Badge on Monday May 31 2021, @09:50PM (#1140587) Homepage Journal

    Even Lisp and related computer languages sleep. But it's called garbage collection.

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