Why Do We Sleep

[DrmDoc]

Hello All,

 

Below are comments I've posted in other forums regarding the nature of sleep. I welcome your thoughts:

 

"If some of us do not know why we sleep, it is because we haven't examined how sleep may have evolved among sleeping species. Nearly every species enters a state of rest that could be interpreted as sleep. This suggests a common evolutionary advantage to the sleep process among sleeping species; i.e., we would not have sleeping species if sleep did not offer some survival advantage to ancestral species.

 

When we examine the neurological components of sleep in most animals, we find that its various attributes arose at varying stages in neural evolution. Contemporary sleep processes in the human brain appear to be mediated by neurons in the literal hypothalamus. Further down the brainstem, other components of the sleep process appear to suggest an earlier evolutionary incarnation of sleep.

 

During the earliy stages of sleep, the brain engages in diminishing activity until the onset of atonia, which is the lost of muscle elasticity. Interestingly, atonia can and does occur in animals without hypothalmic neural structure. This positions atonia as one of sleep's earliest incarnation because it appears to be mediated by neural structures earlier in the brain's evolution than that suggested by the hypothalamus.

 

If the brain evolved from some earlier form, we should be able to find some footprint of that form, which we can trace back to some earlier point. Most researchers agree that the brainstem is a primitive component of our central nervous system. Of the brainstems components, the spinal brain (myelencephalon) appears to be the most primitive segment because it most closely resemble the notochord development we find in existant species of primitive animal life.

 

When we examine the afferent neural systems of the spinal brain, we find those associated with feeding. This infers that ancestral animals at this stage in brain development engaged behaviors requiring the intake of nutrients. Although the efferents neural paths of the spinal brain suggests movement at this stage in earlier ancestral animals, movement most likely evolved with the evolution of the metencephalon where we find more sophistocated afferent neural systems associated with sound detection. The ability to detect sound suggests ancestral animals at the stage where they were orienting themselves either away from or towards sensory stimuli.

 

Early spinal brained animals were probably not as mobile as later metencephlic animals. This suggested lack of mobility infers that these animals had to adopt a stratergy that allowed for survival in the absences of readily available nutrients. In some archeological literature, it has been suggested that the earliest forms of complex life where a combination of plant and animal. During the prolonged absence of sunlight or nutrients in their primodial sea, immobile animals that could suspend their need for sustainance likely had a survival advantage over those that could not. During the atonic stage of sleep, we find a suspension of muscle readiness with energy devotion to organs more critical to our survival. Atonia appears to be mediated by the metencephalon/myelencephalon brainstem segments. This suggests that the earliest components of sleep evolved as a means to sustain survival through periods of prolonged food privation.

 

Although food privation is not a severe concern for some of us, our modern brain rest upon a primitive foundation that was dependent on the periodic suspension of activity to conserve energy for more vital physiological systems. In our brain develpment, evolution built upon its successful systems rather than replace those systems. Sleep evolved from a vestigial need that has become integral to how our contemporary brain functions."

[PhDwannabe]

When we examine the afferent neural systems of the spinal brain, we find those associated with feeding. This infers that ancestral animals at this stage in brain development engaged behaviors requiring the intake of nutrients.

 

I think the word we're looking for here is "suggest," not "infer." With that out of the way: we really don't need the presence of afferent nerves associated with feeding processes in a section of our brain which we share with certain ancestors to suggest that those ancestors, um... needed to eat.

 

Although the efferents neural paths of the spinal brain suggests movement at this stage in earlier ancestral animals, movement most likely evolved with the evolution of the metencephalon where we find more sophistocated afferent neural systems associated with sound detection.

 

Creatures without the ability to detect sound, without a metencephalon, and indeed without a brain are able to move.

 

In some archeological literature, it has been suggested that the earliest forms of complex life where a combination of plant and animal.

 

This is not archeology. Taking the whole passage at once, however:

 

Early spinal brained animals were probably not as mobile as later metencephlic animals. This suggested lack of mobility infers that these animals had to adopt a stratergy that allowed for survival in the absences of readily available nutrients. In some archeological literature, it has been suggested that the earliest forms of complex life where a combination of plant and animal. During the prolonged absence of sunlight or nutrients in their primodial sea, immobile animals that could suspend their need for sustainance likely had a survival advantage over those that could not. During the atonic stage of sleep, we find a suspension of muscle readiness with energy devotion to organs more critical to our survival. Atonia appears to be mediated by the metencephalon/myelencephalon brainstem segments. This suggests that the earliest components of sleep evolved as a means to sustain survival through periods of prolonged food privation.

 

Well, OK, this looks to be a gigantic non sequitur that one of our dear evolutionary bio folks should pick apart themselves. In short, the ability of animals to engage in some kind of metabolic depression or suspension evolutionarily well-predates brains--occurring in many single-celled creatures. And finally:

 

neurons in the literal hypothalamus

 

[headdesk]

 

You said you'd welcome thoughts, DrmDoc. I apologize that none of mine are particularly kind.

[DrmDoc]

I think the word we're looking for here is "suggest' date='" not "infer." With that out of the way: we really don't need the presence of afferent nerves associated with feeding processes in a section of our brain which we share with certain ancestors to suggest that those ancestors, um... needed to eat.[/quote']

 

Clearly, you choose a point of contention by ignoring previous comments for contention sake, which is not productive. The point here is to show how the primitive segments of our brainstem suggests what might have been the primary behavior of the first complex animals with just this neural development and no other. Indeed, living organisms need to feed but that is clearly not the intent of my comments when viewed in context and from the position of one who is interested in enlightened discussion rather than adolescent intellectual one-upmanship.

 

Creatures without the ability to detect sound, without a metencephalon, and indeed without a brain are able to move.

 

Again, my comments here were to show how the primitive aspects of our central nervous system (CNS) suggest the behavior of the first complex animals at the metencephalic stage of neural evolution. Prior developments suggest feeding as a primary pursuit and capability among early complex animals, as might be found among animals anchored to a primordial sea floor. Newer, contiguous development suggests the emergence of gross locomotion in support of what might have been increasingly complex feeding habits. Indeed, there may have been, as at present, organisms capable of movement without a CNS. However, our CNS structure suggests the evolutional path of brain development in the complex animals ancestral to humanity.

 

In some archeological literature' date=' it has been suggested that the earliest forms of complex life where a combination of plant and animal.[/quote']

 

This is not archeology. Taking the whole passage at once, however:

 

Agreed; the word is paleontology. Why we sleep is tied to brain evolution, which is suggested by its recent-to-primitive structure and supported by the similar structures we find among animals in the fossil record.

 

Early spinal brained animals were probably not as mobile as later metencephlic animals. This suggested lack of mobility infers that these animals had to adopt a stratergy that allowed for survival in the absences of readily available nutrients. In some archeological literature' date=' it has been suggested that the earliest forms of complex life where a combination of plant and animal. During the prolonged absence of sunlight or nutrients in their primodial sea, immobile animals that could suspend their need for sustainance likely had a survival advantage over those that could not. During the atonic stage of sleep, we find a suspension of muscle readiness with energy devotion to organs more critical to our survival. Atonia appears to be mediated by the metencephalon/myelencephalon brainstem segments. This suggests that the earliest components of sleep evolved as a means to sustain survival through periods of prolonged food privation.[/quote']

 

Well, OK, this looks to be a gigantic non sequitur that one of our dear evolutionary bio folks should pick apart themselves. In short, the ability of animals to engage in some kind of metabolic depression or suspension evolutionarily well-predates brains--occurring in many single-celled creatures.

 

My intent was to engage in a productive discussion of the sleep process as suggested by its various components in brain evolution and structure. We sleep because the functionality of our recent brain developments is dependent on the vestigial processes of earlier development evolved to sustain the viability of the vital systems, of antecedent animals, through periods of rest and food privation. Rather than engage in equally productive discussion and contribute substantive comments, you'd rather mollify what certainly appears to be a personal esteem issue by selecting passages out of context to support a skewed perception of my comments.

 

neurons in the literal hypothalamus

 

[headdesk][

 

Agreed; the word should have been lateral.

 

You said you'd welcome thoughts' date=' DrmDoc. I apologize that none of mine are particularly kind.[/quote']

 

Perhaps I should have been more specific in welcoming the thoughts of those sincerely interested in engaging insightful discussion rather that self-aggrandizement.

Edited August 16, 2010 by DrmDoc

[PhDwannabe]

you'd rather mollify what certainly appears to be a personal esteem issue

adolescent intellectual one-upmanship

Perhaps I should have been more specific in welcoming the thoughts of those sincerely interested in engaging insightful discussion rather that self-aggrandizement.

 

Let's go ahead and, being civil, keep that out of a discussion of data and scientific hypothesis and theory. Up for contention are: data, hypothesis, theory, logical reasoning, and clarity of expression. Musing about the values, motives, or personalities of the person on the other side of the screen is best left to one's private angry muttering. Lord knows I do a fair amount of it. Onward, then, honorable combatant!

 

Clearly, you choose a point of contention by ignoring previous comments for contention sake, which is not productive. The point here is to show how the primitive segments of our brainstem suggests what might have been the primary behavior of the first complex animals with just this neural development and no other.

 

 

If that was the point, it was unclear to me. Including the word "primary" in the original would have made it clearer. At any rate, if that is the point: do we have any reason to believe that this is sound evolutionary-biological reasoning:

1) The mechanism x exists in our physiology, which allows us to engage in/primarily regulates behavior y.

2) That mechanism x is a remnant/version of some mechanism x' which first existed in some ancestor.

3) The ancestor which saw the initial development of mechanism x' must have also been engaging in behavior y.

4) Behavior y must have been this ancestor's "primary behavior."

 

I don't think either 3) or 4) are anywhere near sound. I'll leave the reader to develop their own analogies about, say, hands and flippers and fins and whatnot.

 

We sleep because the functionality of our recent brain developments is dependent on the vestigial processes of earlier development evolved to sustain the viability of the vital systems, of antecedent animals, through periods of rest and food privation.

 

OK, so here's something. First off, I'm not sure if we could really call these processes "vestiges," since they have clear extant function. The claim here is pretty general--that we sleep because (I think it is more right to say that we can sleep because) ancestors evolved processes... here's where it gets a little stranger... "to sustain the viability of vital systems... through periods of rest and food privation." Two endings there. The first one is somewhat tautological: We can sleep because ancestors evolved processes to sustain systems through periods of rest. What? The second one is the part of your claim that seems to be the most novel: it's a proposed connection between mechanisms responsible for maintaining life through food privation and modern sleep behavior--namely, that the latter has evolved in some way from the former, if I have it right.

 

That's a claim--a scientific claim. It's not insane or stupid or unamenable to the processes of science by any means. One we can work with. I've questioned your chain of logic as regards that claim. I haven't yet seen a parry to that particular attack. Better yet would be the provision of some sort of evidence--evolutionary biological, paleontological, anthropological, for this claim or its ancillaries.

 

 

Edited August 16, 2010 by PhDwannabe

[Marat]

Pathological states in humans suggest some interesting connections between sleep and nutrition. Patients with Kleine-Levin Syndrome, for example, can sleep up to 16 or 18 hours a day, but when they wake up, they often go into an eating frenzy which is disproportionate to the amount of time they have been without food. Renal patients who develop neurological damage preventing them from sleeping more than a few hours at a time have little or no appetite (though there are also other factors involved in this loss of appetite).

[PhDwannabe]

Pathological states in humans suggest some interesting connections between sleep and nutrition. Patients with Kleine-Levin Syndrome, for example, can sleep up to 16 or 18 hours a day, but when they wake up, they often go into an eating frenzy which is disproportionate to the amount of time they have been without food. Renal patients who develop neurological damage preventing them from sleeping more than a few hours at a time have little or no appetite (though there are also other factors involved in this loss of appetite).

 

Quite right--the commonness of strange eating behavior in parasomniacal conditions (organic, or induced) is yet another example. I'd go beyond the word "suggest," however. The mechanism of the connection is reasonably well-understood: behaviors like eating and sleeping, as well as other processes which regulate basal metabolism, all share quite a bit of architecture up there--for eating and sleeping, particularly in the hypothalamic neighborhood. It's difficult to disturb a massive neuroendocrine transshipment center like the hypothalamus--either with a physical lesion or chemical abnormality--without knocking more than one thing off the shelf.

 

This extant overlap of function, however--talking to DrmDoc here, not Marat--doesn't in itself necessarily inform us in specific ways about the evolutionary history of either the region or the functions.

[DrmDoc]

Let's go ahead and, being civil, keep that out of a discussion of data and scientific hypothesis and theory. Up for contention are: data, hypothesis, theory, logical reasoning, and clarity of expression. Musing about the values, motives, or personalities of the person on the other side of the screen is best left to one's private angry muttering. Lord knows I do a fair amount of it. Onward, then, honorable combatant!

 

If you wanted to be civil, you would have set that tone from the outset. Clearly, you did not. Although I'd rather this not be adversarial, I think it's best to have some idea of what could be an opposition's psychology in such discussions. That psychology suggests to me that no matter the evidence, no position I espouse will be perceived as sound. Therefore, this simply becomes a point/counterpoint discussion rather than a cordial and enlightened exchange of ideas, which I had hoped to engage. Nevertheless…:

 

If that was the point, it was unclear to me.

 

It was unclear because you either ignored or didn't understand prior statements outlining the direction of my comments regarding the various components of sleep arising at varying stages in brain evolution. Without some inherent agenda as a hindrance, I think anyone reading those statements will find the direction I outlined quite clear.

 

Including the word "primary" in the original would have made it clearer.

 

I hardly think any wording would have suited given your subsequent comments:

 

At any rate, if that is the point: do we have any reason to believe that this is sound evolutionary-biological reasoning:

1) The mechanism x exists in our physiology, which allows us to engage in/primarily regulates behavior y.

2) That mechanism x is a remnant/version of some mechanism x' which first existed in some ancestor.

2) The ancestor which saw the initial development of mechanism x' must have also been engaging in behavior y.

3) Behavior y must have been this ancestor's "primary behavior."

 

I don't think either 3) or 4) are anywhere near sound. I'll leave the reader to develop their own analogies about, say, hands and flippers and fins and whatnot.

 

If you had read my prior comments, this is what you would have found: Nearly every species enters a state of rest that could be interpreted as sleep. This suggests a common evolutionary advantage to the sleep process among sleeping species; i.e., we would not have sleeping species if sleep did not offer some survival advantage to ancestral species....When we examine the neurological components of sleep in most animals, we find that its various attributes arose at varying stages in neural evolution.…If the brain evolved from some earlier form, we should be able to find some footprint of that form, which we can trace back to some earlier point. Most researchers agree that the brainstem is a primitive component of our central nervous system. Of the brainstems components, the spinal brain (myelencephalon) appears to be the most primitive segment because it most closely resembles the notochord development we find in existent species of primitive animal life….When we examine the afferent neural systems of the spinal brain, we find those associated with feeding. This infers that ancestral animals at this stage in brain development engaged behaviors requiring the intake of nutrients….movement most likely evolved with the evolution of the metencephalon where we find more sophisticated afferent neural systems associated with sound detection. The ability to detect sound suggests ancestral animals at the stage where they were orienting themselves either away from or towards sensory stimuli.

 

And the point: Early spinal brained animals were probably not as mobile as later metencephalic animals. This suggested lack of mobility infers that these animals had to adopt a strategy that allowed for survival in the absences of readily available nutrients…. During the atonic stage of sleep, we find a suspension of muscle readiness with energy devotion to organs more critical to our survival. Atonia appears to be mediated by the metencephalon/myelencephalon brainstem segments. This suggests that the earliest components of sleep evolved as a means to sustain survival through periods of prolonged food privation.

 

Using your analogy to describe the path of the earliest factors leading to the earliest evolved component of sleep (atonia):

 

1 thru 4) Mechanism x exists in what most researchers agree is the most primitive aspect of our CNS that is relatable to the complex animals likely ancestral to humanity. Mechanism x suggests a primary compelling factor in the behavior of early complex species leading to the emergence of the earliest component of sleep behavior (atonia) where mechanism x resides.

 

We sleep because the functionality of our recent brain developments is dependent on the vestigial processes of earlier development evolved to sustain the viability of the vital systems, of antecedent animals, through periods of rest and food privation.

OK, so here's something. First off, I'm not sure if we could really call these processes "vestiges," since they have clear extant function.

 

The components of contemporary sleep emerge from and rest upon functions that are vestiges of an earlier time in our brain's evolution.

 

 

The claim here is pretty general--that we sleep because (I think it is more right to say that we can sleep because) ancestors evolved processes... here's where it gets a little stranger... "to sustain the viability of vital systems... through periods of rest and food privation." Two endings there. The first one is somewhat tautological: We can sleep because ancestors evolved processes to sustain systems through periods of rest. What? The second one is the part of your claim that seems to be the most novel: it's a proposed connection between mechanisms responsible for maintaining life through food privation and modern sleep behavior--namely, that the latter has evolved in some way from the former, if I have it right.

 

Because the tenor of my original post eluded (IMO) your initial understanding, I sought to summarize the intent and direction of my thoughts in as few words as possible. If this was a cordial and enlightened exchange, you likely would have asked me to elaborate further at which point we would have explored the details of how I arrived at my conclusions in more amenable terms and tone. Instead, as it seems, you pounced on somewhat concise individual statements as detailed descriptions and conclusions, which leads to misperceptions and false assumptions.

 

That's a claim--a scientific claim. It's not insane or stupid or unamenable to the processes of science by any means. One we can work with. I've questioned your chain of logic as regards that claim. I haven't yet seen a parry to that particular attack. Better yet would be the provision of some sort of evidence--evolutionary biological, paleontological, anthropological, for this claim or its ancillaries.

 

As I have said, I can provide you with the evidence I relied on to reach my conclusion but they would likely not be sufficient in adversarial discussion. However, for those of more enlightened interest who might be following our little discussion, the Triune theory of brain evolution explores the evolutional stages of brain development defining the brainstem as its most primitive stage. The various components of the sleep process emerging from the brainstem was largely revealed by Dr. Michel Jouvet through a series of papers beginning in the late 1950's and continuing through the to the late '60's (e.g., Jouvet, M., Michel, F., & Courjon, J. [1959], Sur un stade d'activité électrique cérébrale rapide au cours du sommeil physiologique [CR Soc Biol., 153, 1024-1028] and Jouvet, M. [1967], Neurophysiology of the states of sleep [Physiological Reviews, 47(2), 117-177].). The segments of brainstem and the specific neural developments associated with each, as reference in my comments, can be explored at your leisure through any college level neuropsychology or neuroanatomy text (e.g., Kolb and Wishaw's Fundamentals of Human Neuropsychology or Notle's The Human Brain: An Introduction to Its Functional Anatomy.).

 

 

 

.

Edited August 16, 2010 by DrmDoc

[PhDwannabe]

As I have said, I can provide you with the evidence I relied on to reach my conclusion but they would likely not be sufficient in adversarial discussion. However, for those of more enlightened interest who might be following our little discussion, the Triune theory of brain evolution explores the evolutional stages of brain development defining the brainstem as its most primitive stage. The various components of the sleep process emerging from the brainstem was largely revealed by Dr. Michel Jouvet through a series of papers beginning in the late 1950's and continuing through the to the late '60's (e.g., Jouvet, M., Michel, F., & Courjon, J. [1959], Sur un stade d'activité électrique cérébrale rapide au cours du sommeil physiologique [CR Soc Biol., 153, 1024-1028] and Jouvet, M. [1967], Neurophysiology of the states of sleep [Physiological Reviews, 47(2), 117-177].). The segments of brainstem and the specific neural developments associated with each, as reference in my comments, can be explored at your leisure through any college level neuropsychology or neuroanatomy text (e.g., Kolb and Wishaw's Fundamentals of Human Neuropsychology or Notle's The Human Brain: An Introduction to Its Functional Anatomy.).

 

 

I was really referring to some empirical support for the claim that extant sleep physiology is in some way evolved from mechanisms meant for dealing with food privation. Neurophys research from the mid-20th century and neuropsych/neuroanatomy textbooks are probably not going to be good sources for that.

Edited August 16, 2010 by PhDwannabe

[DrmDoc]

I was really referring to some empirical support for the claim that extant sleep physiology is in some way evolved from mechanisms meant for dealing with food privation. Neurophys research from the mid-20th century and neuropsych/neuroanatomy textbooks are probably not going to be good sources for that.

You selectively attack evidence you believe to be irrelevant without proper study or discussion. As I have said, as your reply evince, no sound evidence of significance and relevance to a topic in adverserial discussion would be amenable to the opposition.

[PhDwannabe]

You selectively attack evidence you believe to be irrelevant without proper study or discussion. As I have said, as your reply evince, no sound evidence of significance and relevance to a topic in adverserial discussion would be amenable to the opposition.

 

To throw down evidence which isn't highly relevant to the point, and then resist the questioning of that evidence with "you won't accept anything I'll say!" is a rhetorical tactic, and a bad one.

 

I can't speak for the dozens of lurkers, but I'm still looking for some recent, peer-reviewed evolutionary biological literature which might at least speak to a connection between mechanisms for dealing with food privation and extant sleep physiology. I don't think that's a great deal to ask. In discussions of psychology, I don't cite many whole textbooks--because that's generally unhelpful--and I don't cite many studies from midcentury--because, with a few exceptions, I may as well be citing Aristotle. Sciences move quickly. Support your claim with some kind of recent literature: quote it, and describe how it applies. These aren't particularly novel rules that I'm making up in the middle of a game, here. I've challenged you to support a simple claim, and that is how the support is generally constructed. Do so, and we'll have something substantive to chew over.

 

 

P.S.: Perhaps there is something in those Jouvet articles, etc. which might directly apply to the food-privation-mechanism-extant-sleep-physiology connection. (That'd surprise me, but I'd be pleased to eat those words.) If so, would you be able to quote a section here, or send me the articles? I'm not able to obtain them with my own academic database access. Merci!

[DrmDoc]

To throw down evidence which isn't highly relevant to the point, and then resist the questioning of that evidence with "you won't accept anything I'll say!" is a rhetorical tactic, and a bad one.

 

To prejudge evidence as irrelevant without what seems the slightest consideration or knowledge of that evidence's content suggests your biased conviction, which validates my position regarding evidence in adverserial discussions. And yet, I have provided citations to such evidence, contrary to your claim that I have not.

 

I can't speak for the dozens of lurkers, but I'm still looking for some recent, peer-reviewed evolutionary biological literature which might at least speak to a connection between mechanisms for dealing with food privation and extant sleep physiology. I don't think that's a great deal to ask. In discussions of psychology, I don't cite many whole textbooks--because that's generally unhelpful--and I don't cite many studies from midcentury--because, with a few exceptions, I may as well be citing Aristotle. Sciences move quickly. Support your claim with some kind of recent literature: quote it, and describe how it applies.

 

Your approach notwithstanding, I support my position with the available evidence when no new evidence or evidence to the contrary exists. I consider neuroanatomy texts as reliable guides and resources to the basic available research regarding the functional nature and structure of our CNS. Where the mechanisms for atonia and the afferent neural systems associated with feeding reside in the brainstem have not changed since their initial discovery. That these mechanisms reside in the same segment of brainstem isn't a coincident of evolution. As early as research by Sir Charles Sherrington, atonia has been known to engage when decerebrate animals were not being fed or otherwise physically stimulated. You did receive the proper citations for my thoughts regarding this issue.

 

 

P.S.: Perhaps there is something in those Jouvet articles, etc. which might directly apply to the food-privation-mechanism-extant-sleep-physiology connection. (That'd surprise me, but I'd be pleased to eat those words.) If so, would you be able to quote a section here, or send me the articles? I'm not able to obtain them with my own academic database access. Merci!

 

Now, as an afterthought, maybe there is relevant material in Jouvet's work? Careful, you may ruin my perception of your psychology. All of Dr. Jouvet's work is available online. Try a Google Scholar search.

[Genecks]

Deep homology is a beautiful topic of study.

 

Yes, as I've studied more neuroscience, I've noticed that scientists in the past few decades have remained amazingly ignorant or have neglected studying evolutionary aspects of sleep. Furthermore, many other aspects of brain evolution and phylogenetic relatedness have been ignored. I can understand perhaps ignoring aspects of the brain, because we were not definite (and still aren't of many) about brain cells and their mechanics. But to excuse phylogenetic studies of brain evolution in biochemical and behavioral relatedness seems impractical. Nonetheless, people have attempted to do phylogenetic studies in relation to intelligence, but that's an extreme that is not easily defined nor measured with biochemical tests. Of the ones that come to mind, many were anatomical and simply looked at the macrostructure of the brain, sometimes in relation to body weight.

 

Something I came across in the past year was this:

How Alcohol Blunts Ability Of Hamsters To 'Rise And Shine'

 

Perhaps of the best arguments I've come across for sleep is that it helps reduce stimulation of various neurons. Constant stimulation seems to deplete (or perhaps overexcite) the cell of its function, and sleep enables it to regain a sense of stability. Melatonin buildup also plays in by eventually inducing a desire for sleep. Perhaps the mechanisms to induce sleep came about through various evolutionary stages, during which the hand of evolution and fitness eventually guided humans to require about 8 hours of sleep for a decent amount of mental and physical recovery. Maybe some phylogenetic studies of similar animals would reveal how sleep is similar (or even dissimilar) in species, thus revealing HGH patterns and mental capacity patterns in relation to sleep amount.

 

In general, I think a lot will be found through phylogeny and biochemical experiments.

Edited August 17, 2010 by Genecks

[DrmDoc]

as I've studied more neuroscience, I've noticed that scientists in the past few decades have remained amazingly ignorant or have neglected studying evolutionary aspects of sleep. Furthermore, many other aspects of brain evolution and phylogenetic relatedness have been ignored. I can understand perhaps ignoring aspects of the brain, because we were not definite (and still aren't of many) about brain cells and their mechanics. But to excuse phylogenetic studies of brain evolution in biochemical and behavioral relatedness seems impractical.

 

I welcome your cordial and insightful perspective and agree with much of what you have said. Sleep involves a confluence of neural functions arising from brainstem components evolving at various stages in our CNS's evolution, as its recent-to-primitive contiguous structure suggests. Although we may have a general understanding of the neurological and neurochemical mechanisms of sleep, these mechanisms by themselves do not tell us much about the origin and evolutional path of sleep. When we evaluate these mechanisms in context with how our CNS likely evolve, I think we can form a cogent evolutional perspective of how these components of sleep arose and why they persist today. The individual components explain themselves but, individually, they do not speak to the history of the sleep process. That history provides a fascinating perspective of why we dream—in my opinion.

 

 

Nonetheless, people have attempted to do phylogenetic studies in relation to intelligence, but that's an extreme that is not easily defined nor measured with biochemical tests. Of the ones that come to mind, many were anatomical and simply looked at the macrostructure of the brain, sometimes in relation to body weight.

 

Indeed, macro study doesn't explain the emergence of the individual components that constitute contemporary brain structure. Studying how the function of those components contiguously emerge and fit together offers, in my opinion, a unique perspective on the emergence of mind, memory, consciousness, and various other aspects of brain function.

 

Perhaps of the best arguments I've come across for sleep is that it helps reduce stimulation of various neurons. Constant stimulation seems to deplete (or perhaps overexcite) the cell of its function, and sleep enables it to regain a sense of stability. Melatonin buildup also plays in by eventually inducing a desire for sleep. Perhaps the mechanisms to induce sleep came about through various evolutionary stages, during which the hand of evolution and fitness eventually guided humans to require about 8 hours of sleep for a decent amount of mental and physical recovery. Maybe some phylogenetic studies of similar animals would reveal how sleep is similar (or even dissimilar) in species, thus revealing HGH patterns and mental capacity patterns in relation to sleep amount.

 

Indeed, we know a great deal about what sleep and the absence of sleep do from brain and body. However, the nature of contemporary sleep tells us very little about its initial adaptation or its compelling evolutional circumstance. I began a study of that adaptation and circumstance during research for a book about the dreaming brain, which I wrote several years ago. The experience caused me to question contemporary notions about the confluence of functions that produce mind and consciousness and the significance of specific structural developments. It was fascinating to discover how--through decorticate research--cortical structure and function may not be as essential to some cognitive behaviors as I had thought.

[PhDwannabe]

I'm still shaking in anticipation for that recent, peer-reviewed evolutionary biological evidence which might suggest a connection between mechanisms evolved to deal with food privation and extant sleep physiology.

[Zolar V]

 

Yes, as I've studied more neuroscience, I've noticed that scientists in the past few decades have remained amazingly ignorant or have neglected studying evolutionary aspects of sleep. Furthermore, many other aspects of brain evolution and phylogenetic relatedness have been ignored.

 

I actually never really thought about the topic very much. I have heard of the evolution of the brain with regards to sleep in passing a few times but nevery really thought about it.

 

I think that the reason was some previous bias towards the subject, I have always believed that the reason for sleep was for the conservation of nutrients and to give our body time to do physiological things without needing to adjust to whatever demands we apply to it when we are awake.

If there is an evolutionairy aspect to it then i would follow this line of thinking in essence, sleep allowed us to store nutrients and thus allowed us to use more nutrients during our periods of wakefullness. If you notice, plants do not have a sleep cycle, they have 2 different cycles one while the sun is out and one when it is not. They are constantly active, processing and storing and recycling nutrients, where as animals that use a restfull cycle seem to be more active during the non-restfull cycle.

[DrmDoc]

P.S.: Perhaps there is something in those Jouvet articles, etc. which might directly apply to the food-privation-mechanism-extant-sleep-physiology connection. (That'd surprise me, but I'd be pleased to eat those words.) If so, would you be able to quote a section here, or send me the articles? I'm not able to obtain them with my own academic database access. Merci!

 

To which my response was, "All of Dr. Jouvet's work is available online. Try a Google Scholar search." And now, your reversal:

 

I'm still shaking in anticipation for that recent, peer-reviewed evolutionary biological evidence which might suggest a connection between mechanisms evolved to deal with food privation and extant sleep physiology.

 

Initially you dismiss Jouvet's work as irrelevant without even a glance. Then, in the very same post, you state your willingness to concede it may indeed have some relevance. Now, it seems we are back to square one. To be clear, as stated in prior post, we are looking for an association between the mechanisms for atonia and those for rest and food privation in the segment of brainstem relatable to ancestral animals (Triune Theory). All papers available through Google Scholar (GS) are peer reviewed, including Jouvet's should you once again care to consider them. However, while perusing GS, I found this peer reviewed article suggesting a connection between mechanisms for NREMS (a tonic state) and visceral activities.

 

Villablanca, J. R. (2004). Counterpointing the functional role of the forebrain and of the brainstem in the control of the sleep-waking system. J Sleep Res., 13(3), 179-208.

Specifically:

 

If undisturbed, the motor activity of the decerebrate cat decreases, the W posture tends to collapse and, eventually, the animal lies down in a random position. The eyelids and the nictitating membrane close and the pupils exhibit fluctuating myosis. The eyeballs show slow, often dissociated movements, tending to an inward and downward rotation. The EKG and respiration rate slow down. This state is quite labile as it is easily reversed by exteroceptive stimuli, specially auditory; however, there is a slight tonicity to it, i.e. the stimulus intensity required to reverse the oculo-pupillary pattern is greater when the pupillary diameter is small and has been maintained for a longer time. Nevertheless, myosis never becomes extreme (fissured or slit pupils) and is not tonically maintained for long periods (15–30 min), as described for NREMS in intact cats (Berlucchi et al., 1964). During these quiescence periods the EMG activity attenuates but there are no changes in the brainstem EEG. Indeed, the slow, high-voltage waves which are recorded from the brainstem of intact cats during NREMS are no longer seen after brainstem transection, as also documented by others (e.g. Jouvet, 1962). This is not due to incapacity of the intrinsic brainstem circuitry to support higher voltage EEG activity, as ponto-geniculo-occipital (PGO) waves are generated in the truncated brainstem (see 2.3) and rhythmic waves of as high as 100 μV can be induced pharmacologically (by harmaline; Villablanca and Riobó, 1970; see 4.2).

 

In our original description (Villablanca, 1965a), we cautiously called the above set of events the 'variable myosis stage' of S [sleep], but interpreted it as the 'synchronized or slow wave S of intact cats', now NREMS. We have revised that interpretation (Villablanca et al., 2003) and concluded that NREMS cannot be sustained by the brainstem in decerebrate animals. The reasons are: (i) behaviorally, this is a transient, labile state which is more similar to quietness of the medullary cat or to D [drowsiness] of the intact animal than to true NREMS, this is epitomized by the unstable nature of the pupillary myosis as well as by the absence of somniac and postsomniac NREMS postures; (ii) spindles and slow waves are absent in the truncated brainstem and we now conceive of these events as truly triggering and maintaining D and NREMS, respectively (see 5.2); (iii) the periods of quiescence in our mesencephalic cats are behaviorally very similar to those in Siegel's medullary animals. In the latter cats, single unit activity of reticular neurons only slows down during these periods, albeit without any specific patterning, and we predict that the same would occur in our mesencephalic cats. This absence of true NREMS agrees with the fact that there are not brainstem structures, which can actively sustain NREMS within the brainstem. Indeed, it appears that the only brainstem site currently accepted as NREMS-promoting is the area of the n. tractus solitarious (e.g. Golanov and Reis, 2001; Vertes and Kocsis, 1997). However, this site appears to have, not a local, but an ascending effect mediated either by solitary projections to hypothalamic areas, or indirectly, via the reticular formation. The latter site most likely consists of the medullary cerebral vasodilator area suggesting (Golanov and Reis, 2001) that the role of the solitarius area may be to link visceral activities with S-W [sleep-wake] and other related events.

 

The article suggests that this site, n. tractus solitarious, in the truncated, mesencephalic brainstem is the only area capable of promoting NREMS, which is a tonic state. The viscera association with the solitarius and its NREMS (tonic state) mediation in the brainstem coupled with the unstable nature of tonicity in mesencephalic animals suggest a connection between the need to feed and the sustained tonicity of NREMS in the mesencephalic brainstem. At the very least, this article associates visceral activities with sleep/wake processes through a segment of brainstem relatable to an earlier time in brain evolution according that segments position in the Triune model.

 

Edited August 18, 2010 by DrmDoc

[PhDwannabe]

All papers available through Google Scholar (GS) are peer reviewed

 

Wrong. The one you found did appear to be peer-reviewed, though, so we can certainly work with it. Moving on:

 

The article suggests that this site, n. tractus solitarious, in the truncated, mesencephalic brainstem is the only area capable of promoting NREMS, which is a tonic state

 

Wrong. The article suggests that the NTS is an exception in what could be several areas capable of sustaining NREMS, because it is the only one that is in the brainstem:

 

This absence of true NREMS agrees with the fact that there are not brainstem structures, which can actively sustain NREMS within the brainstem. Indeed, it appears that the only brainstem site currently accepted as NREMS-promoting is the area of the n. tractus solitarious (e.g. Golanov and Reis, 2001; Vertes and Kocsis, 1997).

 

In fact, they even contradict your above assertion in their abstract:

 

...true NREMS- and REMS-generating mechanisms exist exclusively in the forebrain and brainstem, respectively [...] the thalamus engages in both NREMS and W

 

Anyway, let's look at your more modest claim:

 

At the very least, this article associates visceral activities with sleep/wake processes through a segment of brainstem relatable to an earlier time in brain evolution according that segments position in the Triune model.

 

Doc, I'm going to say it again. We don't need to associate or suggest any sort of connection between the functionalities of sleep and anything else in terms of the neurological architecture they share. That is known. I'll re-quote what I said up there:

 

behaviors like eating and sleeping, as well as other processes which regulate basal metabolism, all share quite a bit of architecture up there--for eating and sleeping, particularly in the hypothalamic neighborhood. It's difficult to disturb a massive neuroendocrine transshipment center like the hypothalamus--either with a physical lesion or chemical abnormality--without knocking more than one thing off the shelf.

 

There I was talking about the hypothalamus. It can also be said about the brainstem. We're fixated on the nucleus of the solitary tract, now, are we? Well, solitary tract nucleus pathways also help control the gag reflex. Do you think sleep could be the evolutionary relative of behaviors initially evolved to clear foreign matter from the throat? Using the paradigm of the triune brain, you're making evolutionary arguments based on what's hanging out together in the neuroanatomical neighborhood. The problems with this sort of reasoning are serious. The triune brain model you employ has similar problems, and can help explain what I mean here; it assumes a nearly-exclusive process of addition--new stuff being layered on top of old stuff--rather than a process of modification. It gets laughed at by a lot of current neurobiologists--it's a pop theory. It's really a pretty solid example of the teleological fallacies which plagued evolutionary theory for its first hundred years--it's an obsession with phylogenetic progression. "This progression is viewed as occurring in step with the ascent up the phylogenetic scale. Homoplasty, particularly parallelism and convergence, are not considered as factors in evolution. This unidimensional progression, seemingly under the direction of some imperative, is reminiscent of the now discredited 'predetermined path' theory of apparent steady lines of 'progressive' evolution" (Butler & Hodos, 2005, p. 116).

 

Much as I'd like to bash the triune model for a while, let me get back to the meat of it, so there's no misunderstanding:

 

I'm, as you by now know, most interested in your claim that extant sleep physiology is somehow evolved from earlier functions which dealt with food privation. I still haven't seen any evidence from an evolutionary biological perspective, which I think would be strongest. What you've presented here is some neurophysiological research which one part of sleep behavior (non-rapid eye movement sleep) shares some neurological architecture with other functions. Indeed, the quoted article did not say anything about eating, it noted "visceral activites." The one named visceral activity it seemed to be referring to was that controlled by the medullary cerebral vasodilator area, which is a region of the medulla that helps adjust cerebral blood flow. In terms of advancing upon your thesis, this finding does not really get us anywhere.

 

 

 

 

 

References

Butler, A. B., & Hodos, W. (2005) Comparative vertebrate neuroanatomy: Evolution and adaptation, 2nd ed. Hoboken, NJ: Wiley.

[Ringer]

This whole conversation seems to be jumping around a lot so I'll try to stick with what I think is going on.

 

First, Sleep is a time when the metabolic processes slow as well as a recovery process. It is safe to assume that early hominids didn't hunt or gather at night due to the need for light to gather fruits and berries and such. We, like almost all other animals, need a time to recover and sleep let's us use more energy towards healing, recovering energy, etc. than on cognitive functions, muscle movement, etc.

 

Second, you premise of us having something because it offers a selective advantage is misguided. There are many things that can't be attributed to advantage, i.e. genetic drift, and there are some things that evolved as an offshoot of something that was used in a different way, i.e. the area used to recognize faces often sees faces in anything that is roundish and has certain patterns of shadows. Just because it's there doesn't mean it was needed or helpful, it just didn't harm anything enough to cause the inheritors to die off.

 

Third, your statement about the earliest animals says that they slept because there was a shortage of food, what evidence is this based on? Even with your presumption that early animals didn't move much, who's to say that they didn't move because there was an abundance of food.

[DrmDoc]

Wrong. The article suggests that the NTS is an exception in what could be several areas capable of sustaining NREMS, because it is the only one that is in the brainstem:

I disagree. As my position regards an association between atonia and feeding in the brainstem that could be relatable to the evolutionary process; consideration of other areas are, therefore, irrelevant.

 

This absence of true NREMS agrees with the fact that there are not brainstem structures, which can actively sustain NREMS within the brainstem. Indeed, it appears that the only brainstem site currently accepted as NREMS-promoting is the area of the n. tractus solitarious (e.g. Golanov and Reis, 2001; Vertes and Kocsis, 1997)....solitarius area may be to link visceral activities with S-W [sleep-wake] and other related events.

 

The NTS supports my idea of a tonicity promoting area (via NREMS) of the brainstem, associated with sleep, that could be linked to processes associated with feeding, which involves the viscera.

 

In fact, they even contradict your above assertion in their abstract:

 

...true NREMS- and REMS-generating mechanisms exist exclusively in the forebrain and brainstem, respectively [...] the thalamus engages in both NREMS and W

 

"True NREMS" meaning sustained NREMS. Although the NTS does not generate sustained NREMS, its association with visceral related activities suggests a relationship between those activities and the propagation of sustained NREMS through a primitive element of our CNS.

 

Much as I'd like to bash the triune model for a while, let me get back to the meat of it, so there's no misunderstanding:

 

I'm, as you by now know, most interested in your claim that extant sleep physiology is somehow evolved from earlier functions which dealt with food privation. I still haven't seen any evidence from an evolutionary biological perspective, which I think would be strongest. What you've presented here is some neurophysiological research which one part of sleep behavior (non-rapid eye movement sleep) shares some neurological architecture with other functions. Indeed, the quoted article did not say anything about eating, it noted "visceral activites." The one named visceral activity it seemed to be referring to was that controlled by the medullary cerebral vasodilator area, which is a region of the medulla that helps adjust cerebral blood flow. In terms of advancing upon your thesis, this finding does not really get us anywhere.

 

The Triune theory presents a popular perspective of the brainstem as relatable to an earlier, more primitive incarnation of brain structure, which you have yet to deny. If we agree that brainstem structure suggests an earlier time in brain evolution, then what does that structure suggests about its earlier time? How do we go about the process of accessing what the brainstem suggests about the progression of brain development from an earlier evolution?

 

When evolutional biology provides very little about the emergence of specific behavioral qualities expressed through brain function, do we begin by evaluating the anatomic minutia of each brain segment relatable to existent primitive species with those qualities, then look for similar species in the fossil record, explore the likely compelling evolutionary pressure (environment, population, survival resources, etc.) influencing the behavior of those prior species and, based on those pressures, surmise the demands (e.g., feeding) leading to the emergence of the neural developments (e.g.,Glossopharyngeal and Intermediate Facial), known to promote those behavioral qualities? When, for example, no peer reviewed research exists on the primal emergence of the tonic/atonic expressions of brain function, how do you suggests we access and assess those factors leading to that emergence?

Edited August 18, 2010 by DrmDoc

[Mag]

Just to go back to the original question of why we sleep...

I think we should look at what happens when we don't sleep.

 

Randy Gardner - Awake for 11 Days

 

Sleep Deprivation

 

Rats don't do too well either

[Ahamed]

Hey people.. i have written a blog post regarding this sleeping and the how the brain acts accordingly.. to read this post pls login to http://globaltutor.blogspot.com/2009/12/hello-everybody.html

 

Hope u enjoyed.. Let me hear ur comments in my blog too..

[DrmDoc]

Here's an article describing research suggesting a link between our cortex and that of a species of marine worms, which further extends our brain's evolution back some 600 million years:

 

http://news.discover...uman-brain.html

 

The article goes on to describe how these pre-brain structures in early animals "probably consisted of a group of densely packed cells that received and processed very basic information about food and the environment. The structure may have enabled our ancestors crawling over the sea floor to identify food sources, move towards them, and then later to integrate previous experiences into learning." The goal of this research, the author quotes, "'is to reconstruct and understand the evolution of brains in animals, to trace their neuronal composition and their function from the very beginning of animal evolution to something as complex as today's human brain,'" Aspects of what this article discusses appear to be consistent with some of my comments regarding relatable aspects our central nervous system to an earlier time in its evolution.

Edited September 3, 2010 by DrmDoc

[Ahamed]

imagine the humans remain waken throughout their life time. What actually happens if we do this is, that we will not be able to slow down the gathering of information. Therefore we may not be able to analyse, process the information in a clear way so that we could understand better. According to latest findings, scientists had discovered that there are 2 sections in our brain: Unconscious and conscious brain. When you are awake, you are using your conscious mind. Here, you will be acquiring information from your senses. But how do we save them? So, in order for those memories to get saved you will need some sleep.When you are sleeping you use your unconscious mind. So one of the main reason why you want to sleep is due to memory. And the other is you can get the maximum of your brain when you are sleeping. Sounds weired?

Let me tell you a simple example. Imagine that you are about to choose something from a given varieties of information. For example, when you are choosing your vehicle. At a glance if you choose something, it is more likely to make mistakes but if you think about it in your leisure times and then make your selection, it is more likely that this selection is confident. When you are sleeping, there are alpha waves in your brain being emitted. In this condition you are in fresh and calm mind and you can think more critically that you were awake.

I have written a post regarding this matter with more detail and some tips where you can use your depth mind (unconscious mind) in variety of applications.

Link: http://globaltutor.b...-everybody.html

Edited October 8, 2010 by Ahamed

[DrmDoc]

imagine the humans remain waken throughout their life time. What actually happens if we do this is, that we will not be able to slow down the gathering of information. Therefore we may not be able to analyse, process the information in a clear way so that we could understand better.

 

If you are suggesting information processing as a reason why we sleep, I disagree. The evidence our central nervous system (CNS) provides suggest that the basic processes of sleep evolved in the brainstem before those elements in the cortex associated with the synthesis of information. Although our conscious acuity appears to be enhanced by the sleep process, that is a relatively recent advantage of sleep rather than the primal reason why we sleep.

 

The elements of our brain structure associated with information processing are relatively recent compared to those primitive elements associated with the mediation of our energy stores and autonomic systems. Our recent brain elements arise from and are dependent upon the primitive elements of our CNS for functionality. If the primitive elements do not function efficiently, this can and does affect the efficiency and function of dependent recent elements. The functionality of our brainstem is dependent on the sleep process. When that process is disrupted, it has a rippling affect on hierarchical functions of our brain.

 

According to latest findings, scientists had discovered that there are 2 sections in our brain: Unconscious and conscious brain.

 

According to my read of the latest findings, our brain experiences two distinct functional states of cognitive active rather than some type of sectioning: Waking state [conscious] and the state of dreaming (unconscious).

 

When you are awake, you are using your conscious mind. Here, you will be acquiring information from your senses. But how do we save them? So, in order for those memories to get saved you will need some sleep.When you are sleeping you use your unconscious mind. So one of the main reason why you want to sleep is due to memory. And the other is you can get the maximum of your brain when you are sleeping. Sounds weired?

 

Because our mental acuity and memory is enhanced after sleep periods inclusive of dreaming, some sleep researchers believe this process is some how associated with memory consolidation. If sleep improved our mental acuity and memory, we should find the elderly of sharper mind than they were in their youth since the elderly tend to sleep longer. However, that is not the case. Atonia, rather than dreaming itself, enhances the production of Orexin-A, which has be shown to reverse the affects sleep deprivation with the benefit of dream sleep. If some mental analyses or processing amid dream sleep was essential to the brain's functionality, orexin alone would not have proven as effective in deprivation study. We dream as a consequence of vestigial activity in the brainstem associated with the mediation of our metabolism amid prolonged periods of inactivity and rest. This activity is a vestige of the neural processes ancestal animals likely evolved to endur extended periods of nutrient privation.

Edited October 9, 2010 by DrmDoc

[Ahamed]

You may also refer the following resources...

http://globaltutor.blogspot.com/2009/12/hello-everybody.html