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  • This episode is sponsored by Fabulous, an app that helps you form healthy habits that stick.

    這集是由 Fabulous 贊助播出,Fabulous 是一款幫你建立健康習慣的應用程式。

  • Click the link in the description to get a 25% off a Fabulous premium subscription.

    點擊描述欄的連結可以獲得 Fabulous 高級訂閱的七五折優惠。

  • Let me ask you a question: What came first, sleep or the brain?


  • Many would probably answer that question with "brain", obviously.


  • Except, recent research points out that sleep might not be as connected to the brain as scientists once thought.


  • Because organisms with super simple neural networks can still sleep, sort of like us humans.


  • So, if these organisms can sleep, then what is "sleep", anyways?  


  • Well, there are lots of creatures that need to sleep, but they don't all approach it in the same fashion.  


  • For example, humans usually sleep for several hours in a row, with teenagers being the ones who sleep the most.


  • Wild elephants, though, only sleep for a couple hours a day, sometimes going days without entering a deeper, more restful type of sleep.


  • So, what's the brain doing while these creatures are snoozing?


  • Researchers can measure the electromagnetic signals coming from the brain to get an understanding of what's happening in there during sleep.


  • Let's take dolphins, for example.


  • Their way of sleeping is known as unihemispheric, slow-wave sleep.


  • Which means they sleep with half of their brain.


  • When researchers measured the electromagnetic signals coming from dolphin brains, the signals coming from each side of the brain were completely different.


  • Half of the brain was in slow-wave sleep, while the other side of the brain showed signs of wakefulness.


  • But we can also easily observe other, more outward signs that dolphins are asleep.


  • For example, they might close one eyethe eye opposite the brain hemisphere that's asleep.


  • And they may stick close to the surface of the water so that they're able to easily surface to breathe.


  • And studies investigating sleep in invertebrates, like fruit flies and cockroaches, found that these creatures also do things that signal that they're asleep.


  • These include a decrease in their behavior and responsiveness as well as a change their body posture.


  • So, factoring in the different ways creatures sleep, plus the idea that there are these common tell-tale signs that a creature is sleeping, researchers began to look for sleep all over the tree of life.


  • And they found evidence in a lot of organisms, including some very simplistic creatures, like hydras and jellyfish.  


  • Compared to us humans, their neurons aren't as densely packed together.


  • They're more like a light mesh of neurons than brains.


  • By studying this mesh, researchers can tell more about what the first sleeping creature was like and what it was using sleep for.


  • A potential clue for that first sleeping critter is jellyfish, which can enter that sleep state, leading scientists to believe that sleep evolved more than one billion years ago.


  • And finding where in the tree of life organisms like jellyfish converge with mammals can help researchers uncover the incredibly ancient common ancestor that we share.


  • Now, for creatures with only a sparse mesh of neurons, researchers think that sleep probably plays a role in their metabolism, the amount of energy a creature's body uses to maintain itself.


  • So for organisms that have a simplistic neural network, their bodies are just changing what they do with the available energy.


  • Entering a state of sleep may trigger reactions to occur that can't happen while the creature is awake.


  • Or sleep may just provide enough available energy for these reactions to take place.


  • For example, the nematode C. elegans uses the time it's asleep to grow and repair its tissues.


  • ​​This creature doesn't sleep at regular intervals each day.


  • Instead, it only sleeps after periods of development.


  • And researchers have also found that sleep-deprived hydras pause the daily division of their body cells.


  • Recent research also links metabolism and sleep in organisms with more complex neural networks, like humans.


  • So, sleep is tightly woven into the human body's hormonal and metabolic processes and is vital in keeping the metabolism functioning properly.


  • Which means if you're sleep-deprived or have a sleep disorder, it may negatively impact the body's metabolism.


  • So, animals from humans to critters with just a mesh of neurons can at least sort of sleep, but what if you don't have any neurons at all?


  • That ancient common ancestor between jellyfish and mammals probably had neurons that would have transmitted a signal to the muscles to cause the organism to move.


  • And when it wasn't moving, it would've been considered to be in a sleep state, like how we can measure the outward behavior of sleeping dolphins, elephants, or humans.


  • But the jury is still out on creatures lacking neurons and muscles altogether, like sponges, for example.


  • Measuring something like this has proven to be a challenge because there's no electrical signals to detect, and the sponge doesn't really move in the same way that other animals do.


  • So researchers can't look for a change in body posture as an indicator of sleep.


  • Sponges do have a metabolism; they are, after all, a living, breathing creature that has energy demands.


  • Researchers just haven't yet come up with a way to tell whether these creatures go through a metabolic cycle, pausing some of their activity to use that energy for other things, on a cellular level.


  • A better understanding of whether these kinds of creatures sleep could help answer many questions surrounding sleep.


  • And this, in turn, could help researchers better understand human sleep.


  • Potentially leading to new ways of treating sleep-related diseases or the development of new drugs that target spots in the body previously thought to be completely separate from the sleep process.


  • So, thanks to some of the more simplistic creatures on this planet, scientists have learned that sleep is anything but a simple, one-size-fits-all process.


  • And something else that could help you keep tabs on your sleep is today's sponsor, Fabulous!


  • They're a self-care and habit-forming app developed at Duke University's Center for Advanced Hindsight, and they have over 20 million users.


  • The app is customizable to support your personal goals, like crafting your space to be distraction-free or setting a realistic bedtime goal to have a good night's sleep.


  • And with a Fabulous premium subscription, you also unlock coach sessions and journeys to inspire a shift in mindset, like incorporating small, simple habits in your evening routine.

    透過 Fabulous 的高級訂閱,你也可以解鎖教練課程和激勵心態轉變的旅程,像是把微小簡單的習慣合併成你晚上的例行公事。

  • If you wanna check them out, the first 100 people who click on the link in the description will get 25% off a premium Fabulous subscription.

    如果你想要去看看,前一百位點擊描述欄連結的觀眾可以享有 Fabulous 高級訂閱的七五折優惠。

  • That helps us out too, so, thank you.


This episode is sponsored by Fabulous, an app that helps you form healthy habits that stick.

這集是由 Fabulous 贊助播出,Fabulous 是一款幫你建立健康習慣的應用程式。

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    Julianne Sung 發佈於 2022 年 01 月 24 日