Why has nothing evolved to not need sleep?

[Zeuzzz]

An animal that does not sleep would be at a huge advantage over all other animals as animals are more vulnerable when asleep. Animals go through all the hassle of digging a burrow, or climbing a tree so they are safe when they sleep.

So why have none evolved to counter this large disadvantage and perform the jobs that sleep does while in an awake state?

 

[Capsid]

Viruses/bacteria/fungi don't sleep do they?

 

[aggle-rithm]

An animal that does not sleep would be at a huge advantage over all other animals as animals are more vulnerable when asleep. Animals go through all the hassle of digging a burrow, or climbing a tree so they are safe when they sleep.

So why have none evolved to counter this large disadvantage and perform the jobs that sleep does while in an awake state?

If we had any earthly idea WHY animals need sleep, then we might be able to answer this question.

 

[Twiler]

Because it isn't a sufficiently important advantage to cover the change required to a creature's internal systems?

 

[jmercer]

The first thing is... evolution is a random process. What works continues, and what doesn't tends to disappear. (Depending on how negative the impact is of the failed traits.)

Since it's a random process, while any trait might emerge, there's no guarantee that every possible one will. So that's one possible explanation. Another may be that the biological basis for mammalian and reptilian life here requires a dormancy period; I'll leave that thought for others to expand on, because frankly I don't know enough about it to speak to it. (For example, I can't even tell you if insects have periodic dormancy periods.)

Also, consider the possibility that having periods of dormancy may actually enhance survivability. Even if you were awake, the body needs rest in order to recuperate from activities; were someone were capable of being continuously alert and active, it might result in a much-reduced lifespan... which would certainly curtail opportunities to breed, which in turn would lower the survivability of a given species. Another thing is that many species are specialized in terms of being better at things during day or night. Dormancy during the time when they are least effective at hunting or surviving being hunted might also be a trait that was successful.

All guesses on my part, but just some thoughts on your very interesting question.

 

[Marquis de Carabas]

Being awake is expensive. If one could get away with it, the best option would be more sleep with limited waking time to eat and shtup.

 

[Ivor the Engineer]

An animal that does not sleep would be at a huge advantage over all other animals as animals are more vulnerable when asleep. Animals go through all the hassle of digging a burrow, or climbing a tree so they are safe when they sleep.

So why have none evolved to counter this large disadvantage and perform the jobs that sleep does while in an awake state?

Animals require less energy when they are asleep. In a world where energy sources are scarce, using less increases an individual animal's chances of living to an age where it can pass on its genes.

ETA: MdC and jmercer beat me to it.

 

[Zeuzzz]

If we had any earthly idea WHY animals need sleep, then we might be able to answer this question.

Thats what I suspected.

We spend about 20-25 years of our lives asleep. Spending one third of your life, and not knowing why you do it, and what its purpose is, is one of the biggest mysteries in science in my opinion.

 

[paximperium]

Actually sleeping is an evolutionary advantage.
It helps conserve energy and sleep is believed to aid in processing memory.

 

[Zeuzzz]

Viruses/bacteria/fungi don't sleep do they?

you sure?

Thats a good question actually, do single-celled organisms and simpler multi-celled organisms rest? at what point along the complexity chain does the need for sleep and rest begin?

 

[3point14]

I seem to recall reading that dolphins (and possibly other cetations) sleep with half a brain at a time.

 

[paximperium]

you sure?

Thats a good question actually, do single-celled organisms and simpler multi-celled organisms rest? at what point along the complexity chain does the need for sleep and rest begin?

Well, then you have to define sleep don't you?

A jellyfish shuts down function at night but only in response to light. Bacteria shut down and "hibernate" when there is lack of food. Is that sleep? Not as defined by most scientists.

 

[Marquis de Carabas]

Thats what I suspected.

We spend about 20-25 years of our lives asleep. Spending one third of your life, and not knowing why you do it, and what its purpose is, is one of the biggest mysteries in science in my opinion.

In my opinion, you've got the mystery exactly backwards. In evolutionary terms, the only activity that really matters is reproducing. Why be awake any longer than it takes to do that?

Well, because an animal has to have some energy, so it has to wake up to go get food. And it doesn't want to become food itself, so it can't spend all its time still and unaware. So, you end up with a compromise; an animal sleeps as much as it can get away with sleeping.

 

[Zeuzzz]

Actually sleeping is an evolutionary advantage.
It helps conserve energy and sleep is believed to aid in processing memory.

Yeah, point taken, but, why have none evolved perform the jobs that sleep does while in an awake state? I mean, you can rest and save energy while awake, no altered state of consciousness needed.

The fact that no animals have done so indicates that sleep is incredibly important, for whatever reason.

Dreams too. What's the deal with them? I mean, are they an essential part of sleep? I just watched this documentary which has intrigued me: The Secrets of Sleep - REM and Dreams - Pt1 of 5 they say that the some scientists think that the reason that we sleep is to enable us to dream, based on REM deprivation studies that show that when deprived of REM (the state when you have vivid dreams, the ones you remember) subjects will always catch up on what they missed the next day. Sometimes having twice the usual amount to make up. This was not reported in the other stages apparently.

 

[paximperium]

Yeah, point taken, but, why have none evolved perform the jobs that sleep does while in an awake state? I mean, you can rest and save energy while awake, no altered state of consciousness needed.

The fact that no animals have done so indicates that sleep is incredibly important, for whatever reason.

Dreams too. What's the deal with them? I mean, are they an essential part of sleep? I just watched this documentary which has intrigued me: The Secrets of Sleep - REM and Dreams - Pt1 of 5 they say that the some scientists think that the reason that we sleep is to enable us to dream, based on REM deprivation studies that show that when deprived of REM (the state when you have vivid dreams, the ones you remember) subjects will always catch up on what they missed the next day. Sometimes having twice the usual amount to make up. This was not reported in the other stages apparently.

I have little doubt that sleep has significant importance despite the lack of information its actual use or function. However, sleeping definately has more evolutionary advantage compared to just resting since the brain is the most energy hungry organ we have.

Actually REM is not believe to be needed. There are studies where they let a patient sleep but disrupt their REM cycle and after several weeks of this, there was no problems on the test subjects except for them feeling slightly more tired than normal...there is some new stuff about sleep and it will be interesting to see what's new with the recent biochemical need to sleep.

 

[sol invictus]

Yeah, point taken, but, why have none evolved perform the jobs that sleep does while in an awake state?

But they have - even in the case of (very) large mammals. Did you not bother to read the response above?

 

[JoeEllison]

Why didn't any animals evolve invincibility and heat vision? Those would be an advantage too.

 

[CFLarsen]

It makes extremely good evolutionary sense to sleep: You are safe, you are not spending energy, and you recuperate from a tiresome waking state. When you awake, you have prolonged the time you are here, thereby increasing your chances of reproducing, and making sure your offspring survives.

In evolutionary terms, the only activity that really matters is reproducing. Why be awake any longer than it takes to do that?

Middle-aged couple, humping away. Wife says:

"Oh, Eric.....we've done this so many times that we could be doing it in our sleep. Right?.....Eric? ERIC??"

 

[Ichneumonwasp]

An animal that does not sleep would be at a huge advantage over all other animals as animals are more vulnerable when asleep. Animals go through all the hassle of digging a burrow, or climbing a tree so they are safe when they sleep.

So why have none evolved to counter this large disadvantage and perform the jobs that sleep does while in an awake state?

As others have mentioned, I think you have it a bit backwards. Higher animals are safe when they sleep. Most hide themselves while awake, and they hide while asleep. Sleeping keeps them from being eaten.

I think a large part of the issue has to do with the enormous investment that animals must take for vision. We have two different forms of vision -- one adapted for night living and one adapted for day living. While many animals have a mixture of these two visual systems (humans certainly do), they tend to specialize in one or the other. Diurnal animals are at a disadvantage both for hunting and for being hunted at night. Sleep keeps them from being eaten when they are at their most vulnerable. Switch that about for nocturnal animals and we see the same dynamic.


ETA:
The whole REM story is another issue altogether. The earliest sleepers (phylogenetically) don't have REM sleep, and if you look at animals that have the most REM, they are not humans but echinoderms. It is very likely that REM sleep first evolved as a thermoregulatory mechanism, but it has assumed new roles in other animals over time -- to the point now where it is necessary for memory encoding (or releasing the dreck memories from the day).

 

[Denver]

you sure?

Thats a good question actually, do single-celled organisms and simpler multi-celled organisms rest? at what point along the complexity chain does the need for sleep and rest begin?

Fungal Dreams.
I think that's a term from the 60s.