
Scientists discover the first brainless animal that sleeps - molecule
https://www.washingtonpost.com/news/speaking-of-science/wp/2017/09/21/scientists-just-discovered-the-first-animal-without-a-brain-that-sleeps/
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rayalez
Somewhere I've heard a cool idea that sleep might be the "default" state of
the living organisms. Most of the time you want to rest and conserve energy,
so sleeping is just how we are, it's waking up to get food and procreate is
the "strange" thing we do.

No idea if this makes sense scientifically, but it's fun to think about.

Or maybe animals that walk around during the time when there's no light just
get themselves into trouble more often and end up dying out of the gene pool.
Might as well shut down during the dangerous time and use it for repair.

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tpeo
The only issue with this idea is that it really ... doesn't tie in with
evolution. Because ultimately, the default state of any organism should be to
be attempting to reproduce. But I stress "ultimately", because there's nothing
which impels us to think that needs to be the case at all times. Idling can be
a successful short-term strategy, even if not in perpetuity.

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meri_dian
So what this may be telling us is that sleep is required for beings with nerve
cells, rather than solely for those with concentrated and clearly defined
brains. This would make sense. All animals with brains sleep, but diversity of
brain configuration and design exhibited across all of these different animal
species would indicate that there's no single aspect of a brain that demands
sleep, and therefore sleep is not an emergent property of collections of
neurons forming brains but something the neurons themselves demand in order to
function.

~~~
jldugger
Possible. Or it could just be light as a confounding signal -- they get energy
from it, after all, and animals with brains and eyes will spend energy more
efficiently during the day.

A much older article on jellyfish sleep suggests this proposed advantage, at
least:
[https://search.proquest.com/openview/c958b584511e462a64623c5...](https://search.proquest.com/openview/c958b584511e462a64623c59b7a6bd0a/1?pq-
origsite=gscholar&cbl=40810)

~~~
meri_dian
Well I was thinking that light could impact the availability of their food
source and so what the researchers interpret as sleep is just some other form
of energy conservation, but the 'groggy' behavior of the jellyfish in their
one experiment made me think that their energy conserving state does involve
their neurons and so at that point it's hard to distinguish energy
conservation from sleep.

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Khanthulhu
Title is technically correct (the best kind of correct) but jellies do have a
nervous system. Its a net if a few hundred neurons.

Here's to hoping this research helps is discover why we evolved to sleep.

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pstuart
Isn't the latest thought that it's to take the brain down for maintenance to
flush out debris from processing done during the day? (citation needed)

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amelius
But why didn't our brain evolve to take the debris out _while_ it s working?

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pstuart
Unqualified anonymous internet answer: it's probably too busy.

I believe the brain actually shrinks slightly and channels expand to aid in
the flushing.

Anectdata: note how when you're really tired you can't think clearly? Also,
how (apparently) if one goes without sleep for too long then the brain suffers
irreparable damage.

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cetalingua
What is even more interesting is why exactly do they "sleep" at night? Do they
have some sort of circadian rhythm? They are filter feeders, so the time of
the day should not be that important, after all they can filter feed at night?
Maybe it is a byproduct of being in lab? Since they are fed during the
daytime, they might have "adjusted" to the lab schedule? They need light
though, for their photosynthesizing symbionts.

~~~
Someone
They ([http://travelnq.com/australian-box-
jellyfish/](http://travelnq.com/australian-box-jellyfish/)) or their food
([https://www.nature.com/scitable/blog/saltwater-
science/what_...](https://www.nature.com/scitable/blog/saltwater-
science/what_makes_plankton_migrate)) might move vertically between day and
night, with the jellyfish being unable to follow their food on part of their
depth range. For example, jellyfish might get sunburn at low depths.

(Aside: that first link, from 2014, already states that box jellyfish sleep,
so this doesn’t seem to be as new as this article claims it to be. What (I
guesstimate) is new is that they did pharmacological work to show that the
jellyfish didn’t simply ‘not move’)

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yourkin
Not an expert on jellyfish physiology, but might there be a distinction
between "a sleep-like state" and being plain "tired"? After doing some
physical activity animals tend to need some rest. Exhaustion is much less of
an exciting phenomenon than sleep is.

~~~
cetalingua
Sleep is typically defined by the brain waves activities, delta waves, theta
waves, etc., each corresponding to a specific sleep stage. These are
physiological markers of sleep. There are also states of "quiet wakefulness"
that share behavioral characteristics of sleep, like immobility, for example,
but are not sleep per se.

Many "simple animals" like a fly, or a caterpillar or a bee have periods of
inactivity that could be an example of rest. But sleep and rest are not the
same. If we put brain waves aside, we are left with the behavioral definition
of sleep: it is a state of reduced awareness of the surroundings, there will
be some latency in arousal, it is reversable, and it is associated either with
immobility or at least reduced activity. This study obviously used this
definition, so it is not exactly being "tired".

~~~
yourkin
Thank you for articulating the difference between the two. Can it not be the
case with exhaustion also, that awareness and/or reaction times are reduced?
Cognition certainly is affected after strain in higher order animals and
muscle cells need to replenish ATP.

Removing brain waves from the equation, it seems like the whole question of
what attests for sleep gets blurry.

~~~
cetalingua
Sleep is not just "reduced" cognition, it is an entirely different state all
together. In sleep thalamus becomes a gatekeeper that makes sure that stimuli
cannot get through (although the important ones still do, like a baby cry will
nearly always awaken a mother, even a faint cry will do). So, again, it is
more radical than "quiet wakefulness" due to exhaustion.

Now, with "lower" animals it gets tricky, because all we have is a behavioral
definition of sleep. But still, it makes a distinction of reduced awareness,
arousal latency. Can we call it "sleep" in these animals, jellies included?
Maybe not, maybe it is some sort of proto-sleep state?

~~~
pitcharoad
I'm not convinced because your answer doesn't address the nervous activity of
these lower animals. Maybe they don't exhibit any at all in that state, but
there's no reason to preclude this diffuse, sparse network from exhibiting
patterns exhibiting precursors to sleep comparable to at least one of the
human sleep phases.

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peterburkimsher
The researchers lost sleep to research sleep.

A follow-up question I'd like to see researched is jet lag. Why do the
jellyfish sleep during those hours? Can they adjust their circadian rhythm to
a different time zone?

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itchyjunk
Maybe sleep is linked to neurons? I did read a comment about plants sleeping
but i haven't researched it yet.

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nub3
In my humble opinion every animal consistent of multiple cells alive on this
planet developed sleep for just one reason: the very same reason plants sleep.
Our planet has a night phase and without sun little energy is left. So as a
consequence the best one can do is to clean up internal processes or go into
some sort of energy saving mode. Ofc this is heretic to some individuals...

But Ockham's razor tells me I'm right.

~~~
Scriptor
This makes sense for plants and cold-blooded animals, which rely on light/heat
respectively in order to function well.

This doesn't explain the huge number of nocturnal animals that sleep during
the day and are active at night.

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Udik
If your life (hunting, mating) happens at night, why would you waste energy
staying active during the day?

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polemic
whynotboth.gif

Seriously though, the existence of nocturnal animals kinda puts that argument
to bed. While there might be selection pressure to specialise within day _or_
night cycles, it's simply not plausible that _no_ animal, in the vastness of
the biospehere, has not generalised to do both, without some critical and
fundamental flaw.

~~~
pitcharoad
there might be a differential equation that describes a small part of beings
(not a "huge number") benefitting from the free energy that diurnal animals
might be at night. There's an equilibrium that's clearly preferential to
daylight animals.

Point in case, bats as my primary example seem to be pretty archaic, with
highly developed specializations, but nothing really highly developed. Which I
see as an expression of the low entropy in the dark (the signal to noise ratio
for sound is rather good at night though). Deep see animals are mostly
outliers inhabiting a niche, as well. Whereas people as the highest developed
species, if I may say so myself, don't even quite get along with crossing the
day-night boundaries, I don't see your argument at all. You are rather proving
the point.

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ColanR
> “When you start working on something totally crazy, it's good to get data
> before you tell anybody,” Abrams said.

It's too bad that this seems to be the environment that our up-and-coming
generation of scientists operate in.

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tzs
Moderators: the title should be changed to the actual article title, which is:

"Scientists just discovered the first brainless animal that sleeps"

The submitted title, "Scientists just discovered the first animal without a
brain that sleeps", is ambiguous. In addition to the correct meaning, it could
also have meant the first animal whoe brain does not sleep.

~~~
GuiA
Are there animals who sleep but whose brains don’t sleep?

Are there animals who don’t sleep but whose brains sleep?

While ambiguous from a purely grammatical point of view, it does not seem
ambiguous from a “common sense” point of view.

~~~
wavefunction
It seems that a variety of animals exhibit at least phases of sleep where one
hemisphere or part of a brain is asleep while the other is awake:

[https://en.wikipedia.org/wiki/Unihemispheric_slow-
wave_sleep](https://en.wikipedia.org/wiki/Unihemispheric_slow-wave_sleep)

~~~
wutbrodo
Not to mention the fact that the article is literally about finding the
_first_ animal that did something, so using past data is pretty useless.

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siproprio
They only found out now about teenagers?

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ehutch79
spoiler: it's merely the avatar of a 4th dimensional eldritch horror and is
actually studying the scientists before treating our realm as a cheap buffet.

