4 ms·

The function of sleep in animals is largely obscure. One thing we do know for certain is that it is necessary, it is needed in "dumb" animals as well as in you

by pcrh 5mo ago

The function of sleep in animals is largely obscure. One thing we do know for certain is that it is necessary, it is needed in "dumb" animals as well as in you and I. If an animal can't sleep it will eventually die. I don't think that applies to the activity described in the OP. Does their LLM "die" if it can't perform the function described?

bayarearefugee 5mo ago
> Does their LLM "die" if it can't perform the function described? If you don't periodically clean the context, an LLM effectively goes insane in terms of outputs. If the LLM were fully controlling a physical system (like a robot body) that contained it the resulting insanity of an ever-growing, never cleaned context would likely result in some sort of death-like event.
- pcrh 5mo ago
  That's probably the closest analogy posted here. It's still weak, though. An LLM without constant human input is likely more similar to a bicycle that starts to lose its gyroscopic balance as it moves more slowly, a human can however keep a stationary bicycle upright (while riding it).
Windchaser 5mo ago
I don't think it's necessarily correct to think of sleep in terms of "it is necessary for animals or they will die". It might be more useful to think of it as "it was so useful that animals who slept outcompeted all the animals who didn't". Meaning: it might just provide a big advantage. I don't want to overextend and assume that any advantage extends to LLMs. That rest-and-recuperate advantage might also extend to LLM-based AIs. Or maybe not, and the rest-and-recuperate is mainly useful for biology-based organisms. But there is some logic to it. > The function of sleep in animals is largely obscure. In my understanding, it's well-understood that sleep is used to consolidate and store long-term memories (amongst other functions, like cell and muscle repair). They've found this memory-consolidation-during-sleep even in relatively simple animals like bees.
- palmotea 5mo ago
  > I don't think it's necessarily correct to think of sleep in terms of "it is necessary for animals or they will die". It might be more useful to think of it as "it was so useful that animals who slept outcompeted all the animals who didn't". You're talking about different things: biological necessity and evolutionary benefit. You can find out about the former by preventing an animal from sleeping (but otherwise provide all other needed things), and seeing if it will eventually die.
  - sillysaurusx 5mo ago
    > You can find out about the former by preventing an animal from sleeping (but otherwise provide all other needed things), and seeing if it will eventually die. That is actually almost impossible to do. The rat study was as close as we’ve ever come, and it’s still debated whether the rats died due to lack of sleep or some other mechanism, since the autopsy couldn’t confirm a cause of death. (It could have been due to the way the experiment ran, for example, not the lack of sleep.)
    - michaelmrose 5mo ago
      What about fatal familial insomnia in humans
      - vitamark 5mo ago
        If I remember correctly, fatal insomnia shares most symptoms with other prion diseases (in which there might be no lack of sleep involved), so it's probably the brain damage that causes death, not insomnia itself.
- pcrh 5mo ago
  Sleep-like states exist in animals with nervous systems with a complexity above that found in flatworms, even snails sleep. Sleep therefore appears to be an essential characteristic of more complex biological nervous systems, i.e. biological computers, should you care to stretch the analogy. The more complex the nervous system, the greater the requirement for sleep. What is described in the OP is therefore not a specific characteristic of sleep. It may however be a "useful" rhetorical device. I do however object to the extensive use of such rhetorical tricks in the conversations that surround LLMs. For example, why does a consumer-grade LLM display "thinking" while it is actually sending data from my computer to some datacentre, processing it, and sending the result back? Equally, why does it output human-emotive phrases such as "sorry" when such computation is revealed to be incorrect? Such rhetorical tricks, and more, likely underlie to a large degree the popularity of LLMs, despite their actual performance being clearly below what the rhetoric implies.
adastra22 5mo ago
There is a lot that is known about sleep. We don't know everything and there are large gaps in our knowledge, but there is also a lot that we do know. And this research explicitly tried to emulate the things we know that sleep does do. Calling it "sleep" is warranted, imho.
- rendx 5mo ago
  "Despite myriad studies, there is still no consensus on why sleep is needed for survival." https://www.nature.com/articles/d41586-025-00964-w https://www.nature.com/articles/d41586-025-00964-w (2025)
  - Earw0rm 5mo ago
    Probably because it evolved very early (like before bilateral symmetry, multi layer body cavity, or kidneys early... maybe even before multicellular animals early) and so has been incorporated as an essential pillar into multiple processes layered on top of that fundamental architecture.
    - fc417fc802 5mo ago
      You've merely stated observations about the context and the process that led to it. That doesn't in any way answer the question of what it's actually doing that's so essential.
      - jjk166 5mo ago
        It is not necessary to answer the question of what it's doing that is essential to know a subset of what it is doing.
        fc417fc802 5mo ago
        I don't think your response is coherent. The question was "why is it needed". In context the meaning is clearly to ask what it's doing that's essential and (it follows) why those things are essential. The subsequent response did not (as you suggest) articulate some subset of nonessential things done during sleep. Rather it rattled off plausible (and widely understood) aspects of the process that could have led to the current situation. Even if it had listed concrete activities that would still not have made for a meaningful answer. The first clue that something is wrong should be that the linked article is recent and prominent. Thus short a brand new groundbreaking development we can be reasonably certain that a random commenter on the internet will not be sensibly rebutting the claims (and certainly not in the span of ~2 sentences).
ben_w 5mo ago
> If an animal can't sleep it will eventually die. Very few animals fail to eventually die even with as much sleep as they want. But before death, there is a loss of cognitive function from sleep deprivation, and we observe this too with AI whose context windows get too full. While we don't know very much about sleep, my understanding is that we do have a long list of things that we do during it, we just don't really understand if sleep is necessary for each of them or simply a convenient opportunity for it. There's lots of things biology does in response to easy-to-detect proxy signals instead of the real thing they care about: Our sensation of needing to breathe more is based on too much carbonic acid in our blood, not lack of oxygen, which is why in general nobody is allowed in an elevator with a liquid nitrogen dewar; Our natural distaste for incest is based on who we grew up with, not our actual DNA; Get too cold and some people suddenly feel warm and want to (and some do) take all their clothes off even though that would just make them hypothermic even faster. Being asleep may trigger the things we need to get done, but that doesn't mean sleep is *fundamentally* necessary for the things we need to get done. It could be just that it happens to be the way our biochemistry is wired, and we may find some other way to trigger those things. The quotation given by djeastm would by my guess for what a dream is, and why we have them. But we don't spend all our time asleep, dreaming. And I'd be the first to say that my guess isn't worth much, as I'm not a brain scientist.
- jyounker 5mo ago
  > Being asleep may trigger the things we need to get done, but that doesn't mean sleep is fundamentally necessary for the things we need to get done. It could be just that it happens to be the way our biochemistry is wired, and we may find some other way to trigger those things. We now have evidence for REM sleep in spiders(1). Our last common ancestor with spiders predates the development of nervous systems. This strongly suggests that sleep (and specifically REM sleep) serves some function important enough that it has independently evolved in both protostomes and dueterostomes. (And probably multiple times within the protostomes, being present in both cephalopods and jumping spiders.) There may be some commonality in the origin of the ion channels, but I'll lay money that the requirements for sleep are more of a result of general information processing requirements. (1)https://www.pnas.org/doi/10.1073/pnas.2204754119 https://www.pnas.org/doi/10.1073/pnas.2204754119
palmotea 5mo ago
> The function of sleep in animals is largely obscure. Also, there's different kinds/stages of sleep, which probably perform different functions. For instance, REM may do something like the GP describes, consolidating memories and processing learning. Deep sleep may do something else (I vaguely recall some stage of sleep is used by neurons to clear certain waste products).
sillysaurusx 5mo ago
> If an animal can't sleep it will eventually die. That turns out to be un-settled science. No human has ever died from lack of sleep. People point to “fatal familial insomnia” as a counterexample. But they die to the disease, not the lack of sleep. In a series of controlled experiments, rats and fruit flies did die from lack of sleep. But no one has yet proven that it holds true for vertebrates except for rats. In other words, it could be true that “among vertebrates, only rats die of sleep deprivation.” So “if an animal can’t sleep, it will eventually die” is actually quite hard to prove, and depending on how you look at it, somewhat easy to disprove by the fact that rats and fruit flies were so difficult to kill from sleep depravation alone. Personally I’m skeptical of the rat study too. Claude amends this: > What they did not establish: the mechanism. On autopsy, “no anatomical cause of death was identified.” The rats showed weight loss despite eating more, body temperature problems, and skin lesions, but nothing that pointed to a clean cause. So no, they could not say a rat “died from sleep deprivation alone” in the sense of identifying what sleep loss did to the body to kill it. They showed a strong association under tight controls, not a proven causal pathway.
- ambicapter 5mo ago
  So? You don't need a proven causal pathway to state that a glass heads towards the ground every time you brush it off a table.
  - sillysaurusx 5mo ago
    Scientifically you do, otherwise you can’t claim that lack of sleep was the cause of death. It could be an artifact of how the experiment was run, or any number of other factors. It’s not a small quibble to point out that the central argument (“animals need sleep or they’ll die”) may be mistaken.
- dijit 5mo ago
  > No human has ever died from lack of sleep. As far as I understand it, there is a disease that destroys your brain's ability to produce sleep. Once you have it, you suffer total, progressive insomnia and die within roughly 6–18 months. Scientists debate whether it's the underlying brain damage or the sleeplessness itself that causes death, but the two are inseparable in practice, and sleep deprivation is considered the leading candidate. Separately, the longest anyone has stayed awake under controlled conditions was 11 days, which produced severe cognitive impairment, paranoia, and hallucinations; suggesting the body deteriorates rapidly without sleep. It's probably not wise to state your original claim as established fact.
libria 5mo ago
Is a volcano described as dormant (dormire, literally sleep) also inaccurate and deeply problematic? BTW, it's not anthropomorphized as sleep has existed long before humans. "Sleep" is just used in their context to describe a non-interactive mode and they didn't lean heavily into zoomorphic - I think you mean - parallels. You're grinding an axe on a single term. What is your broader hangup with them using the term "sleep"? > Does their LLM "die" if it can't perform the function described? We're reaching an age where LMGTFY should now be Let Me LLM That For You. Have you tried asking an LLM this question about the article? I believe it answers it very well.
crabbone 5mo ago
I think sleep serves multiple functions. For example, anyone who works out in any-what systematic way knows that sleep is essential for muscle grow. You can't skip on sleep if you want to get fitter. And this probably has very little to do with the more sophisticated functionality of the brain, rather it allows for some process in muscle tissue to happen. So, whether the LLM "dies" in any sense may or may not be important for what "sleep" is defined to be in this article. It's quite possible that sleep also affects endocrine system in animals or hormones etc... and that's what's causing death, not necessarily anything to do with how brain functions.
deleted 5mo ago
[deleted]
naasking 5mo ago
> Does their LLM "die" if it can't perform the function described? It dies in terms of usefulness if it can't stay up to date with new knowledge. That is, it will no longer be used and thus effectively die off.
exe34 5mo ago
LLMs also don't mate, but we can still talk about how they remember or forget things. The meaning of words change. Some of those changes are useful.
nextaccountic 5mo ago
> The function of sleep in animals is largely obscure. This just obscures the conversation IMO. We know a great deal of functions that sleeping performs. We don't know everything. For some reason this prevents us for using this word in a computing context? What do you think about sleep(1) in Unix? Also.. > Does their LLM "die" if it can't perform the function described? what "death" means in the context of a computer program?

by pcrh 5mo ago

bayarearefugee 5mo ago

> Does their LLM "die" if it can't perform the function described? If you don't periodically clean the context, an LLM effectively goes insane in terms of outputs. If the LLM were fully controlling a physical system (like a robot body) that contained it the resulting insanity of an ever-growing, never cleaned context would likely result in some sort of death-like event.

pcrh 5mo ago
That's probably the closest analogy posted here. It's still weak, though. An LLM without constant human input is likely more similar to a bicycle that starts to lose its gyroscopic balance as it moves more slowly, a human can however keep a stationary bicycle upright (while riding it).

Windchaser 5mo ago

I don't think it's necessarily correct to think of sleep in terms of "it is necessary for animals or they will die". It might be more useful to think of it as "it was so useful that animals who slept outcompeted all the animals who didn't". Meaning: it might just provide a big advantage. I don't want to overextend and assume that any advantage extends to LLMs. That rest-and-recuperate advantage might also extend to LLM-based AIs. Or maybe not, and the rest-and-recuperate is mainly useful for biology-based organisms. But there is some logic to it. > The function of sleep in animals is largely obscure. In my understanding, it's well-understood that sleep is used to consolidate and store long-term memories (amongst other functions, like cell and muscle repair). They've found this memory-consolidation-during-sleep even in relatively simple animals like bees.

palmotea 5mo ago
> I don't think it's necessarily correct to think of sleep in terms of "it is necessary for animals or they will die". It might be more useful to think of it as "it was so useful that animals who slept outcompeted all the animals who didn't". You're talking about different things: biological necessity and evolutionary benefit. You can find out about the former by preventing an animal from sleeping (but otherwise provide all other needed things), and seeing if it will eventually die.
- sillysaurusx 5mo ago
  > You can find out about the former by preventing an animal from sleeping (but otherwise provide all other needed things), and seeing if it will eventually die. That is actually almost impossible to do. The rat study was as close as we’ve ever come, and it’s still debated whether the rats died due to lack of sleep or some other mechanism, since the autopsy couldn’t confirm a cause of death. (It could have been due to the way the experiment ran, for example, not the lack of sleep.)
  - michaelmrose 5mo ago
    What about fatal familial insomnia in humans
    - vitamark 5mo ago
      If I remember correctly, fatal insomnia shares most symptoms with other prion diseases (in which there might be no lack of sleep involved), so it's probably the brain damage that causes death, not insomnia itself.
pcrh 5mo ago
Sleep-like states exist in animals with nervous systems with a complexity above that found in flatworms, even snails sleep. Sleep therefore appears to be an essential characteristic of more complex biological nervous systems, i.e. biological computers, should you care to stretch the analogy. The more complex the nervous system, the greater the requirement for sleep. What is described in the OP is therefore not a specific characteristic of sleep. It may however be a "useful" rhetorical device. I do however object to the extensive use of such rhetorical tricks in the conversations that surround LLMs. For example, why does a consumer-grade LLM display "thinking" while it is actually sending data from my computer to some datacentre, processing it, and sending the result back? Equally, why does it output human-emotive phrases such as "sorry" when such computation is revealed to be incorrect? Such rhetorical tricks, and more, likely underlie to a large degree the popularity of LLMs, despite their actual performance being clearly below what the rhetoric implies.

adastra22 5mo ago

There is a lot that is known about sleep. We don't know everything and there are large gaps in our knowledge, but there is also a lot that we do know. And this research explicitly tried to emulate the things we know that sleep does do. Calling it "sleep" is warranted, imho.

rendx 5mo ago
"Despite myriad studies, there is still no consensus on why sleep is needed for survival." https://www.nature.com/articles/d41586-025-00964-w https://www.nature.com/articles/d41586-025-00964-w (2025)
- Earw0rm 5mo ago
  Probably because it evolved very early (like before bilateral symmetry, multi layer body cavity, or kidneys early... maybe even before multicellular animals early) and so has been incorporated as an essential pillar into multiple processes layered on top of that fundamental architecture.
  - fc417fc802 5mo ago
    You've merely stated observations about the context and the process that led to it. That doesn't in any way answer the question of what it's actually doing that's so essential.
    - jjk166 5mo ago
      It is not necessary to answer the question of what it's doing that is essential to know a subset of what it is doing.
      - fc417fc802 5mo ago
        I don't think your response is coherent. The question was "why is it needed". In context the meaning is clearly to ask what it's doing that's essential and (it follows) why those things are essential. The subsequent response did not (as you suggest) articulate some subset of nonessential things done during sleep. Rather it rattled off plausible (and widely understood) aspects of the process that could have led to the current situation. Even if it had listed concrete activities that would still not have made for a meaningful answer. The first clue that something is wrong should be that the linked article is recent and prominent. Thus short a brand new groundbreaking development we can be reasonably certain that a random commenter on the internet will not be sensibly rebutting the claims (and certainly not in the span of ~2 sentences).

ben_w 5mo ago

> If an animal can't sleep it will eventually die. Very few animals fail to eventually die even with as much sleep as they want. But before death, there is a loss of cognitive function from sleep deprivation, and we observe this too with AI whose context windows get too full. While we don't know very much about sleep, my understanding is that we do have a long list of things that we do during it, we just don't really understand if sleep is necessary for each of them or simply a convenient opportunity for it. There's lots of things biology does in response to easy-to-detect proxy signals instead of the real thing they care about: Our sensation of needing to breathe more is based on too much carbonic acid in our blood, not lack of oxygen, which is why in general nobody is allowed in an elevator with a liquid nitrogen dewar; Our natural distaste for incest is based on who we grew up with, not our actual DNA; Get too cold and some people suddenly feel warm and want to (and some do) take all their clothes off even though that would just make them hypothermic even faster. Being asleep may trigger the things we need to get done, but that doesn't mean sleep is *fundamentally* necessary for the things we need to get done. It could be just that it happens to be the way our biochemistry is wired, and we may find some other way to trigger those things. The quotation given by djeastm would by my guess for what a dream is, and why we have them. But we don't spend all our time asleep, dreaming. And I'd be the first to say that my guess isn't worth much, as I'm not a brain scientist.

jyounker 5mo ago
> Being asleep may trigger the things we need to get done, but that doesn't mean sleep is fundamentally necessary for the things we need to get done. It could be just that it happens to be the way our biochemistry is wired, and we may find some other way to trigger those things. We now have evidence for REM sleep in spiders(1). Our last common ancestor with spiders predates the development of nervous systems. This strongly suggests that sleep (and specifically REM sleep) serves some function important enough that it has independently evolved in both protostomes and dueterostomes. (And probably multiple times within the protostomes, being present in both cephalopods and jumping spiders.) There may be some commonality in the origin of the ion channels, but I'll lay money that the requirements for sleep are more of a result of general information processing requirements. (1)https://www.pnas.org/doi/10.1073/pnas.2204754119 https://www.pnas.org/doi/10.1073/pnas.2204754119

palmotea 5mo ago

> The function of sleep in animals is largely obscure. Also, there's different kinds/stages of sleep, which probably perform different functions. For instance, REM may do something like the GP describes, consolidating memories and processing learning. Deep sleep may do something else (I vaguely recall some stage of sleep is used by neurons to clear certain waste products).

sillysaurusx 5mo ago

> If an animal can't sleep it will eventually die. That turns out to be un-settled science. No human has ever died from lack of sleep. People point to “fatal familial insomnia” as a counterexample. But they die to the disease, not the lack of sleep. In a series of controlled experiments, rats and fruit flies did die from lack of sleep. But no one has yet proven that it holds true for vertebrates except for rats. In other words, it could be true that “among vertebrates, only rats die of sleep deprivation.” So “if an animal can’t sleep, it will eventually die” is actually quite hard to prove, and depending on how you look at it, somewhat easy to disprove by the fact that rats and fruit flies were so difficult to kill from sleep depravation alone. Personally I’m skeptical of the rat study too. Claude amends this: > What they did not establish: the mechanism. On autopsy, “no anatomical cause of death was identified.” The rats showed weight loss despite eating more, body temperature problems, and skin lesions, but nothing that pointed to a clean cause. So no, they could not say a rat “died from sleep deprivation alone” in the sense of identifying what sleep loss did to the body to kill it. They showed a strong association under tight controls, not a proven causal pathway.

ambicapter 5mo ago
So? You don't need a proven causal pathway to state that a glass heads towards the ground every time you brush it off a table.
- sillysaurusx 5mo ago
  Scientifically you do, otherwise you can’t claim that lack of sleep was the cause of death. It could be an artifact of how the experiment was run, or any number of other factors. It’s not a small quibble to point out that the central argument (“animals need sleep or they’ll die”) may be mistaken.
dijit 5mo ago
> No human has ever died from lack of sleep. As far as I understand it, there is a disease that destroys your brain's ability to produce sleep. Once you have it, you suffer total, progressive insomnia and die within roughly 6–18 months. Scientists debate whether it's the underlying brain damage or the sleeplessness itself that causes death, but the two are inseparable in practice, and sleep deprivation is considered the leading candidate. Separately, the longest anyone has stayed awake under controlled conditions was 11 days, which produced severe cognitive impairment, paranoia, and hallucinations; suggesting the body deteriorates rapidly without sleep. It's probably not wise to state your original claim as established fact.

libria 5mo ago

Is a volcano described as dormant (dormire, literally sleep) also inaccurate and deeply problematic? BTW, it's not anthropomorphized as sleep has existed long before humans. "Sleep" is just used in their context to describe a non-interactive mode and they didn't lean heavily into zoomorphic - I think you mean - parallels. You're grinding an axe on a single term. What is your broader hangup with them using the term "sleep"? > Does their LLM "die" if it can't perform the function described? We're reaching an age where LMGTFY should now be Let Me LLM That For You. Have you tried asking an LLM this question about the article? I believe it answers it very well.

crabbone 5mo ago

I think sleep serves multiple functions. For example, anyone who works out in any-what systematic way knows that sleep is essential for muscle grow. You can't skip on sleep if you want to get fitter. And this probably has very little to do with the more sophisticated functionality of the brain, rather it allows for some process in muscle tissue to happen. So, whether the LLM "dies" in any sense may or may not be important for what "sleep" is defined to be in this article. It's quite possible that sleep also affects endocrine system in animals or hormones etc... and that's what's causing death, not necessarily anything to do with how brain functions.

deleted 5mo ago

[deleted]

naasking 5mo ago

> Does their LLM "die" if it can't perform the function described? It dies in terms of usefulness if it can't stay up to date with new knowledge. That is, it will no longer be used and thus effectively die off.

exe34 5mo ago

LLMs also don't mate, but we can still talk about how they remember or forget things. The meaning of words change. Some of those changes are useful.

nextaccountic 5mo ago

> The function of sleep in animals is largely obscure. This just obscures the conversation IMO. We know a great deal of functions that sleeping performs. We don't know everything. For some reason this prevents us for using this word in a computing context? What do you think about sleep(1) in Unix? Also.. > Does their LLM "die" if it can't perform the function described? what "death" means in the context of a computer program?