Sleep

by **OrjoWan** Sat Aug 28, 2010 1:35 am

بسم الله الرحمن الرحيم
السلام عليكم ورحمة الله وبركاته

Sleep

Sleep is a naturally recurring altered state of consciousness
with relatively suspended sensory and motor activity, characterized by
the inactivity of nearly all voluntary muscles

It is distinguished from quiet wakefulness by a decreased
ability to react to stimuli, but it is more easily
reversible than hibernation or coma

Sleep is a heightened anabolic state, accentuating the growth
and rejuvenation of the immune, nervous, skeletal and muscular systems
It is observed in all mammals, all birds, and many reptiles,
amphibians, and fish

Sleep stages

In mammals and birds, sleep is divided into two broad types
rapid eye movement (REM) and non-rapid eye movement
NREM or non-REM) sleep)

Each type has a distinct set of associated physiological,
neurological, and psychological features
The American Academy of Sleep Medicine (AASM) further
divides NREM into three stages: N1, N2, and N3,
(the last of which is also called delta sleep or slow-wave sleep (SWS

Sleep proceeds in cycles of REM and NREM, the order normally being
N1 → N2 → N3 → N2 → REM

There is a greater amount of deep sleep (stage N3)
early in the night, while the proportion of REM sleep increases
later in the night and just before natural awakening

The stages of sleep were first described in 1937 by Alfred Lee Loomis
and his coworkers, who separated the different electroencephalography (EEG)
features of sleep into five levels (A to E), which represented the spectrum from wakefulness to deep sleep

In 1953, REM sleep was discovered as distinct, and thus William Dement
and Nathaniel Kleitman reclassified sleep into four NREM stages and REM
The staging criteria were standardized in 1968 by Allan Rechtschaffen
"and Anthony Kales in the "R&K sleep scoring manual

In the R&K standard, NREM sleep was divided into
four stages, with slow-wave sleep comprising stages 3 and 4.
In stage 3, delta waves made up less than 50%
of the total wave patterns, while they made up more than 50% in stage 4
Furthermore, REM sleep was sometimes referred to as stage 5

In 2004, the AASM commissioned the AASM Visual Scoring
Task Force to review the R&K scoring system
The review resulted in several changes, the most significant being
the combination of stages 3 and 4 into Stage N3
The revised scoring was published in 2007 as The AASM Manual
for the Scoring of Sleep and Associated Events
Arousals and respiratory, cardiac, and movement events were also added

Sleep stages and other characteristics of sleep are commonly
assessed by polysomnography in a specialized sleep laboratory
Measurements taken include EEG of brain waves, electrooculography (EOG)
of eye movements, and electromyography (EMG) of skeletal muscle activity
In humans, each sleep cycle lasts from 90 to 110 minutes on average
and each stage may have a distinct physiological function
This can result in sleep that exhibits loss of consciousness
but does not fulfill its physiological functions
(i.e., one may still feel tired after apparently sufficient sleep)

:king:

OrjoWan

by **هدوء** Sat Aug 28, 2010 7:47 pm

Thanks alo0ot

^^

by **OrjoWan** Tue Aug 31, 2010 10:27 pm

Thanks
dear ,
هدوووووء

OrjoWan

Sleep

Sleep

Re: Sleep

Re: Sleep