Can someone find me a scientific definition of sleep  that could be
understood by a layperson?

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Request for Question Clarification by tutuzdad-ga on 12 Nov 2004 20:19 PST

Is this what you are looking for?

?Sleep is defined as "a reversible behavioral state of perceptual
disengagement from, and unresponsiveness to the environment"

SOURCE:
Carskadon, M. A., and Dement, W. C. (1994). Normal human sleep: An
overview. In Dement, Kryger, and Roth (Eds.), Principles and Practices
of Sleep Medicine (pp. 16-25). Philadelphia: Saunders.

Sleep Disordered Breathing: Diagnosis and Treatment
By Gene R. Dahl, RRT, PSGT, Chief Technician, Sleep Laboratory
Presented at: Jonathan M. Wainwright Memorial VA Medical Center Walla Walla, WA 
January 14, 1997 
http://www.bmi.net/grd7958/sleep/sdb.html

??????..

Other sources confirm this definition:

?Sleep is defined as a state of unconsciousness from which a person
can be aroused. In this state, the brain is relatively more responsive
to internal stimuli than external stimuli.?

EMEDICINE
http://emedicinehealth.com/articles/42421-1.asp

Please let me know what you think about this as an answer.


Regards;
Tutuzdad-ga

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Clarification of Question by timespacette-ga on 13 Nov 2004 08:39 PST

Hi Tutuzdad, thanks for asking . . .

I was hoping for a more descriptive explanation on what happens to the
brain at the onset of sleep, and/or through it's several phases. 
Since the whole concept of 'consciousness' is so mysterious, there
probably isn't a scientific description of what that is, or of
unconsciousness, or the various levels of sleep, except to describe
the 'effects' like being unresponsive to the environment, etc.  Am I
getting any closer to a clear question?

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Request for Question Clarification by tutuzdad-ga on 13 Nov 2004 12:27 PST

Yes you are but unfortunatly, to answer your question would be to
solve a great mystery. It seems that scientists know about as much
about the dynamimcs of sleep as they do post-mortem conditions. The
definition I offered is fundamentally what scientists currently
understand sleep to be, but of course the study goes on.

tutuzdad-ga

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Clarification of Question by timespacette-ga on 14 Nov 2004 14:43 PST

Hello tutuzdad,
thanks; I know..  why not go ahead and post this as the answer?

Dear timespacette-ga:

Thank you for accepting my answer. I'll repost my comment here for the
purposes of officially closing your question:

?Sleep is defined as "a reversible behavioral state of perceptual
disengagement from, and unresponsiveness to the environment"

SOURCE:
Carskadon, M. A., and Dement, W. C. (1994). Normal human sleep: An
overview. In Dement, Kryger, and Roth (Eds.), Principles and Practices
of Sleep Medicine (pp. 16-25). Philadelphia: Saunders.

Sleep Disordered Breathing: Diagnosis and Treatment
By Gene R. Dahl, RRT, PSGT, Chief Technician, Sleep Laboratory
Presented at: Jonathan M. Wainwright Memorial VA Medical Center Walla Walla, WA 
January 14, 1997 
http://www.bmi.net/grd7958/sleep/sdb.html

??????..

Other sources confirm this definition:

?Sleep is defined as a state of unconsciousness from which a person
can be aroused. In this state, the brain is relatively more responsive
to internal stimuli than external stimuli.?

EMEDICINE
http://emedicinehealth.com/articles/42421-1.asp

Regards;
Tutuzdad-ga

thanks again

May I suggest that a better phrasing of your question would be:

What is a scientific definition of sleep that can be readily
understood by a layperson?

Timespacette,

You might be interested in some of the material in this answer to a
somewhat similar question:

http://answers.google.com/answers/threadview?id=382592

Hi Pink,

Thank you for that link; it's very interesting and a good response. I
also am a Six Feet Under fan, though I don't have a television (GA is
entertainment enough...) and I have to watch very old reruns on DVD
sets, so I'm never in the know about the current drama . . .

I too experienced a whole vivid 'dream' while under anesthetic, in
which I left my body and watched the operation from about twenty feet
up. I also know someone who was in an airplane crash in some snowy
mountains; the whole time during the rescue says she was experiencing
being on a warm tropical island instead of in freezing temperatures. 
Interesting what our brains can create, huh?  Sort of like your
automatic screensaver . . .

At the moment, as you can see from the above 'clarification' I guess
I'm looking for a scientific description of consciousness in it's
various states; now wondering if it exists . . .

ts

Here's a good article on sleep, as viewed by electroencephalography (EEG):

http://www.emedicine.com/neuro/topic688.htm