Neurology of Sleep.pdf...........................

Sleep
Cns regulating system
Electroencephalogram

1. Neuropsychology of Sleep

2. Intro
How do you know when to sleep and when to wake up?
This is dependant on our circadian (circa: approximately, diem: day) rhythm
Regulated by light and dark signals, information is received by the retina which is
converted into electrical signals and sent to the hypothalamus
Within you Hypothalamus (your internal thermostat), is a group of nuclei called the
Suprachiasmatic nucleus which is responsible for regulating the sleep cycle. IT
does so by communicating with different parts of the brain such as the pons and
pineal gland to release sleep hormones

3. SCN regulating systems
Pineal Gland
-Produces melatonin
-Responsible for slowing down heart rate, breathing and produce sleep
Brain stem
-Plays a role in arousal and sleep as damage to this part can put you in a
vegetative state/coma
-The reticular activating system/ formation (band of fibers): arousal,
consciousness. It blocks information from the body to the cortex.

4. Pons
-Muscle relaxation: puts body in a paralysed state during REM sleep
Neurotransmitters
-Decrease in serotonin will decrease alertness
-Decrease in dopamine will shut of pleasure/reward system
-Decrease in Acetylcholine will reduce muscle movement
-Increase in GABA will bring body to rest by inhibiting brain parts from talking
to each other

6. Electroencephalogram (EEG)

-Measures electrical activity in the brain
-Different sleep cycles have different waves
-Electrodes attached to the skull is attached to the machine
-When youre awake, beta waves have high frequency(close peaks and
dips)/low amplitude(height of the highs and lows)
-When you’re feeling sleepy, you enter nonREM1 and brain starts producing
theta waves. You experience hypnic jerks and hypnagogic hallucination (false
sensory experience)
-In nonREM2, body processes start slowing down. Primarily comrpises of
theta waves. Sleep spindles (brief bursts of brain activity) and K-complex
(high delta waves with drops) can be observed on the EEG. This happens
since information is trying to enter but is being stopped as a requirement for
sleep.

7. EEG
-nonREM3 has low frequency and high amplitude Delta waves. This is a deep
sleep cycle. Body releases growth hormones and repairs itself. This is also
the stage where sleep disorders arise such as sleep walking/talking, bed
wetting. From here your body start going back to nonREM1.
-Before body starts to wake up, we enter REM sleep where brain waves look
like wakefulness. This is where majority dreaming occurs yet body muscles
have paralysis. It is also known as Paradoxical sleep. Important in memory
and learning.
-Each full cycle lasts about 90 minutes from nonREM1 to REM and with each
passing cycle, REM becomes longer and REM 3 shorter

9. Memory consolidation during REM sleep
Implicit memories are consolidated during REM meanwhile explicit during
nonREM. This shifting of memory, consolidation and reconsolidation happens
during sleep and wake and can present as daydreaming and night dreaming

10. REM brain areas
The peribrachial area is important for
initiating REM sleep and is associated with
related behaviour. Contain cholinergic nuclei
which project to MPR to induce muscle
paralysis otherwise one may start acting out
dreams.

11. Non REM disorders
-Insomnia: disorder of slow-wave sleep
-Drug dependant Insomnia: because of overuse of sleeping, you built
tolerance
-Narcolepsy: slow wave sleep disorder in which a person falls asleep
uncontrollably. Can be due to gene mutations producing orexin peptides.
-Sleep apnea: inability to breath during sleep due to inflammation or soft palate
blockage resulting in fatigue

12. Disorders of REM sleep
-Sleep paralysis: inability to move during deep sleep because of bodys
inhibition of motor neurons. Usually during progression towards wakefulness
one experiences hallucinations which is combined with paralysis.
Exaggerated by caffeine, stress and sleep deprivation.
-Cataplexy: sudden and transient episode of muscle weakness accompanied
by full conscious awareness
-Hypnopompic hallucinations are hallucinations that occur in the morning as
you're waking up
-Hypnagogic hallucinations are hallucinations that happen as you're falling
asleep