User:Cancername/WIP/Sleep basics: Difference between revisions

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Created page with "Activity and alertness is reduced during sleep. While sleep affects the entire body, it most strongly affects the nervous system. Many important bodily functions, like waste cleanup and memory processing are supported by sleep. [PSG section about how to measure brain, eye, muscle activity here] == Sleep stages == There are two kinds of sleep stage: rapid eye movement (REM) sleep and non-REM sleep. Non-REM Sleep has stages, which start at light sleep and progressively g..."
 
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Activity and alertness is reduced during sleep. While sleep affects the entire body, it most strongly affects the nervous system. Many important bodily functions, like waste cleanup and memory processing are supported by sleep.
Activity and alertness is reduced during sleep. While sleep affects the entire body, it most strongly affects the nervous system. Many important bodily functions, like waste cleanup and memory processing are supported by sleep. There are two kinds of sleep: rapid eye movement (REM) sleep and non-REM sleep. Non-REM Sleep has stages, which start at light sleep and progressively get deeper. In REM sleep, the eyes move quickly, notably, most dreams occur in it. NREM sleep stages are numbered from 1 to 3, from lighter to deeper. REM and Non-REM sleep alternates, repeating in cycles of around 90 minutes.


[PSG section about how to measure brain, eye, muscle activity here]
== Measurement ==
[[File:EEG Brainwaves.svg|thumb|upright|The differently named frequency bands of neural oscillations, or brainwaves: delta, theta, alpha, beta, and gamma.]]


== Sleep stages ==
Sleep originates in the brain. The brain communicates within itself using electrical signals, they can be measured using electroencephalography (EEG), where electrodes are attached to the scalp and the resulting signals are measured. Additionally, eye movement is an indicator of sleep, we can measure the electrical signals causing eye movements using electrooculography (EOG), which involves attaching electrodes around the eye. Finally, skeletal muscle movement can also be used to measure sleep, and by attaching electrodes to skeletal muscle, its activation can be measured as an electrical signal, this is called electromyography (EMG). Other tests are also performed, however, these three are most useful to distinguish sleep stages. Together, these methods are called polysomnography (PSG).
There are two kinds of sleep stage: rapid eye movement (REM) sleep and non-REM sleep. Non-REM Sleep has stages, which start at light sleep and progressively get deeper.
 
=== Brainwaves ===
Brainwaves, or neural oscillations, are repeating patterns visible in EEG. Normally, EEGs show activity in frequencies ranging between 1 and 30 [[Wikipedia:Hertz|Hz]] and 20 to 100 [[Wikipedia:Volt|μV]]. There are different named categories of neural oscillations characterized by [[Wikipedia:Frequency|frequency]]. When awake and alert, an EEG shows high-frequency, low-voltage oscillations, while alpha waves are produced during relaxation.
 
{| class="wikitable" style="margin:auto"
|+ Oscillation types
! Name
! Frequency range
|-
| Delta
| 0.5-4 Hz
|-
| Theta
| 4-7 Hz
|-
| Alpha
| 8-13 Hz
|-
| Beta
| 13-30 Hz
|}
 
== Stages ==
=== REM ===
The defining characteristic of REM sleep is that eye movement is constant and fast. The brainwaves during REM sleep are similar to wakefulness. REM sleep is associated with muscle relaxation, long visual emotional vivid dreams disconnected from daily life, increased pulse, blood pressure, brain metabolism, and levels of [[Wikipedia:Acetylcholine|acetylcholine]]. [significance?] [vital?]


=== NREM1 ===
=== NREM1 ===
Non-REM sleep stage 1, also called light sleep, is the lightest stage of sleep and comprises around 5% of total sleep time. It generally lasts around 1-5 minutes. In light sleep, the sleeper may be aware, and believe themselves not to be awake. [source] [PSG characteristics] [notable events and happenings] [significance?] [vital?]
Non-REM sleep stage 1, also called light sleep, is the lightest stage of sleep and comprises around 5% of total sleep time. It generally lasts around 1-5 minutes. In light sleep, the sleeper may be aware, and believe themselves to be awake. [source] [PSG characteristics] [notable events and happenings] [significance?] [vital?]
 
=== NREM2 ===
[definition] [PSG characteristics] [notable events and happenings] [significance?] [vital?]


== Sleep cycles ==  
=== NREM3 ===
These stages are arranged in repeating cycles, typically lasting around 90 minutes [variance?]. [what order of sleep stages?] [differences between consecutive sleep stages]
[definition] [PSG characteristics] [notable events and happenings] [significance?] [vital?]


== Effect of sleep ==
== Cycles ==
Stages are arranged in repeating cycles, typically lasting around 90 minutes ± 20 minutes. [what order of sleep stages?] [differences between consecutive sleep stages]
 
== Effects and functions ==
[functions of sleep] [effects on particular conditions]  
[functions of sleep] [effects on particular conditions]  


== References ==
== References ==
* {{Cite book| publisher = StatPearls Publishing| last1 = Patel| first1 = Aakash K.| last2 = Reddy| first2 = Vamsi| last3 = Shumway| first3 = Karlie R.| last4 = Araujo| first4 = John F.| title = StatPearls| chapter = Physiology, Sleep Stages| location = Treasure Island (FL)| access-date = 2025-06-08| date = 2025| chapterurl = http://www.ncbi.nlm.nih.gov/books/NBK526132/| pmid = 30252388}}
* Information about EEG from: {{Cite book| edition = 5th| publisher = McGraw-Hill medical| isbn = 978-0-07-139011-8| title = Principles of neural science| location = New York| date = 2013 |chapter=50. Seizures and Epilepsy}}
 
* Information on stages, cycles and characteristics from:  {{Cite book| edition = 5th| publisher = McGraw-Hill medical| isbn = 978-0-07-139011-8| title = Principles of neural science| location = New York| date = 2013 |chapter=51. Sleep and Dreaming}}
* {{Cite journal| doi = 10.1038/nrn895| issn = 1471-003X| volume = 3| issue = 8| pages = 591–605| last1 = Pace-Schott| first1 = Edward F.| last2 = Hobson| first2 = J. Allan| title = The neurobiology of sleep: genetics, cellular physiology and subcortical networks| journal = Nature Reviews. Neuroscience| date = 2002| pmid = 12154361}}
* General information from: {{Cite book| publisher = StatPearls Publishing| last1 = Patel| first1 = Aakash K.| last2 = Reddy| first2 = Vamsi| last3 = Shumway| first3 = Karlie R.| last4 = Araujo| first4 = John F.| title = StatPearls| chapter = Physiology, Sleep Stages| location = Treasure Island (FL)| access-date = 2025-06-08| date = 2025| chapterurl = http://www.ncbi.nlm.nih.gov/books/NBK526132/| pmid = 30252388}}
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