Why do we sleep?

Pythagorean

Oops, I didn't catch this, didn't see anybody else comment on it yet. This isn't true. The body needs sleep. In fact, rats, when forced to stay up, developed open sores that would not heal and their hair started falling out. Even in humans, a significant portion of wound healing depends on sleep.

Of course, the brain has important house-keeping during sleep cycles, too. There is a large amount of transcription and cellular trafficking that occurs when light cues disappear, particularly pertaining to proteins like fabp7 and psd9, important forming and regulating synaptic junctions.

rodsika

I read that in those rats forced to stay awake.. they just died weeks later. They didn't do any autopsies. But are there other studies where the cause were established? There we can know exactly what parts are affected and why.

Pythagorean

Those rats that died... died with sores and hair loss.

http://ukpmc.ac.uk/abstract/MED/2928...yuHZZRGGfbk.20

And another study cites the above journal to investigate REM sleep deprivation in particular.

Effects of sleep deprivation on wound healing
L. MOSTAGHIMI, W. H. OBERMEYER, B. BALLAMUDI, D. MARTINEZ–GONZALEZ, R. M. BENCA
Journal of Sleep Research
Volume 14, Issue 3, pages 213–219, September 2005

http://onlinelibrary.wiley.com/doi/1...455.x/abstract

rodsika

But that's not the cause of their death. Sores and hair loss are just external features. What is the internal cause?


So you mean only Non-REM Sleep Deprivation can affect wound healing?

Pythagorean

Nobody claimed that; all I said was that the rest of your body needs sleep too, not just your brain.

Nobody knows the exact cause of death; probably because there's multiple failures that happen. You're essentially skipping an important book-keeping phase in a self-organized system.

No, I just said sleep deprivation in general.

This one study shows that REM sleep deprivation alone doesn't seem to account for it (based on their methods and interpretations). It's an important distinction between that and the statement you've made above. In fact, it's become a problem in the literature lately with null-hypothesis rejection tests that people confuse negative statements with the opposite of their positive statements. You can read more about that here:

http://au.academia.edu/JesperWSchnei...ch_assessments

rodsika

Do you have listings for the numbers of hours of sleeps of insects?

Can you name one living thing that doesn't require sleep?

Ryan_m_b

It's unclear if insects sleep, they definitely exhibit sleep like behaviour (I.e daily periods of inactivity) but we've got no real way of knowing how similar this phenomenon is to sleep in other classes of organism.

As for naming organisms that don't sleep: plants fungus and microorganisms. They have circadian cycles but done actually sleep.

Monique

Fruit flies sleep, the definition is 5 minutes of inactivity. Caffeine will reduce their sleep. During the time they sleep they'll exhibit resistance to activity when they're stimulated, similar to our sleep. Also, by forcing flies to stay awake they will actually accumulate sleep-debt, when they're given the chance to sleep they'll sleep for longer and deeper. Fruit flies are used as a model to study sleep, for example: http://www.ncbi.nlm.nih.gov/pubmed/18591491

RabbitWho

Were those rats the same rats that were kept awake by being forced to stay standing on a ledge and if they relaxed they would fall off the ledge and into some water and have to climb up again?

What about rats that could rest but not sleep? Wouldn't they heal the same? Is it really specifically sleep that the body needs or just periods of rest?

Pythagorean

I'm not sure. All the literature says "sleep deprivation".

Gilliland et al., 1989; Kushida et al., 1989 are the two major studies. If you want to pursue your question in the literature, you can find all works citing these studies with Google Scholar and look at the methodologies section of these studies themselves.

rodsika

Hi, I noticed I lose weight when I lack sleep. Is it possible the higgs were involved? How do you discount this possibility?

"Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth." - Sir Arthur Conan Doyle

Evo

I'm surprised this wasn't referenced.

http://www.ncbi.nlm.nih.gov/books/NBK19961/

Another good read.

http://serendip.brynmawr.edu/exchange/node/1690

and

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2656292/

oh heck

http://www.google.com/search?sourcei...llll0&aqi=g-K1

Drakkith

Absolutely not.

If this is the quote you want for all your posts you can put it in it's own place in the options menu or something in the control panel. That way you don't need to put it in every time and people won't quote it when replying.

rodsika

It is said that the human brain is the most complex object in the universe. This means biological system are more complex and efficient or compact than any machine. Since biological system needs sleep. Does this mean any Artificial Intelligence (A.I.) machines in the future need to sleep too? If not.. how can it be.. biological beings exceeds any machines.. for example.. you can't create a bacteria or virus out of nano machines because living system already use atom scales in the molecular parts. Since machines need to follow the living as model. Then future machine A.I. need sleep too?

Drakkith

There is no real "meaning" in what you have said here. What is your criteria for judging the complexity of an object? One could argue that since we are all part of the Milky Way galaxy, which is easily classified as an "object", that the Milky Way is the most complex object in the universe.

I don't agree. MANY features of living creatures are horribly inefficient, large, or likewise worse off than equivalent mechanical devices. My CCD camera for my telescope is far more capable of detecting light than my eye is, and has equal resolution over the entire chip, unlike the retina of the eye. The muscles in your body are much less efficient than a hydraulic system that is not only capable of meeting the same standards as our one of our limbs, but easily surpasses it in terms of strength and doesn't NEED to be as complicated to perform the same actions. (Complexity doesn't mean something is better)

On the flip side there are plenty of biological components that we cannot replicate yet to be as reliable or perform the same functions in the same environments. Hence why we can't just stick new hearts and lungs into people anytime we want.

The point is that it isn't that one or the other is better or worse. They are simply different.

We don't know. I don't see why it would be though. Remember that the human body is not just a program that runs within a computer like an AI is. The body requires rest to repair and regenerate itself, along with whatever neurological stuff it may need to do in the brain. An AI is just a program without a physical body that it needs to repair. (Though you could give it one if technology was sufficiently advanced I suppose)

Since when are machines required to follow living creatures as a model? Have you ever seen an animal with a transmission and wheels? How about the inner workings of a generator such as electromagnets?

kushan

Well , I read something about evolution .
I can say sleep came to existence in most organisms while evolving .
When the first rudimentary photosensitive tissue developed , we can say sleep also developed in the same era (Not the same day , as evolution is a long process) .
And it is known , most if not all organisms , show some sort of light sensitivity.
The living world acquired this new tool and slowly slowly started becoming dependent on it.
Earth receives light half of the time , and there is a relation between no light and sleeping , the organisms were so dependent on light that they had to find out a way to skip the night (NOTE: this is all in terms of evolution and selectivity no one is deciding here who gets what ) . And slowly this form of hibernation or lack of physical activity became sleep as we know now. In this course some organisms developed better photoreceptors than the others , but sleep was still in their genes .Using survival of the fittest theorem I imagine these organism found that hunting (searching for food) at night was more profitable than in the day . Since these organisms could outperform many in the nighttime, they are what we call nocturnal beings . They sleep aswell , but not in the time frame of other organisms generally .