EEG, SLeep and Circadian Rhythms Flashcards
What is sleep?
State of unconsciousness from which individual can be aroused by normal stimuli, light, touch, sound etc. Predictable and Cyclical
Why is sleep important
Range of functions, including:
-Reduced general metabolism
-Clearing out from CNS
- Neuronal plasticity
-Sorting of memories (Learning and memory)
-Cognition
–Immune function
Where does sleep originate from in the brain?
Pons and below
What 2 centers exist in the reticular formation and how do they control our sleepiness?
Awake (arousal) and Sleep centrers,
Awake (Orexin) stimulates wakefulness, whilst the sleepy one stimulates sleep. They wake up and overtake the other when it comes to bed time or waking up.
How do:
Adenosine
Delta Sleep inducing peptides (DSIPS)
melatonin
serotonin
contribute to sleep?
Adenosine - levels increase throughout the day, at threshold sends us to sleep. Adenosine receptors are antagonised by caffeine -> keeps us awake.
Delta Sleep inducing peptides (DSIPS) - induce sleep (duh)
melatonin - darkness causes its production by the pineal gland. In humans and other non nocturnal animals it sends us to sleep.
serotonin - related to melatonin. Potentially a precursor.
Where is the suprachiasmatic nucleus? How does what does it do?
In the hypothalamus
Involved in circadian rhythm and production of melatonin. (removes inhibition of melatonin production when darkness falls)
How does light affect the laevel of melatonin?
Light causes inhibition opf melanin production
What is Orexin?Defective Orexin signalling causes what disease?
Melatonin inhibits orexin (Hypocretin) - excititory neurotransmittor released from hypothalamus. - awake and aroused hormone.
If defective, known as narcolepsy (can spontanwously fall asleep
What does frequency of brainwaves determine, go from long waves to short waves
State of conciousness
So the longer the wave, the more asleep we are.
Long: anasthesia - sleep - relaxed awake - focussed awake - Tonic-clonic Epilepsy = Short
Increased amplitude (on EEG) means what i terms of neuranoal concentration
The higher the deeper the sleep
(because the more brain activity, the more crosswaves etc and so the more some of the height has been cancelled out etc)
Alpha waves
Beta waves
Theta waves
Delta
wave patterns mean what state of alertness?
Alpha waves - A for Awake but relaxed. (imagine A as one wave) high frequency and mid amplitude
Beta waves - B for Buzzing (imagine B as waves, fits 2 in the same amount of space as A) very high frequency, low amplitude
Theta waves - Mum asleep at the Theatre (early stages of sleep) - long waves and varying amplitude
Delta waves - The BIG BOYS - D for the DEEPEST sleep you ever had which was on Delta airlines. Biggest amplitude and lowest frequency.
Why low B waves amplitude but alert and awake state?
Because so much activity with waves in all directions that some of the waves cancel each other out. (asynchronous activity)
5 stages of sleep - what are they and what waves do they have
1 - light sleep. Slow eye movements (NON REM) -> Theta (high amp, low frequency)
2 - mid sleep. Eye movements stop. Has “Sleep Spindles” -> Theta (but slower frequency)
3 - deep sleep (part 1) -Delta (high amplitude and very slow, decreasing spindle activity)
4 - deepest sleep - exclusively Delta
(5) - REM sleep - Looks like awake on graph
Pattern goes something like 1,2,3,4,3,2,REM, 2,3,4,3,2,REM,2,3,2,REM,2,3,2,REM
When do we usually go into deep sleep?
earliest part of the night a couple of times
What happens in deep sleep?
Body relaxes (reduced vascular tone (and therefore BP)), reduced metabolic rate (and so decreased body temp), and resp rate
V active hippocampus
physiological appearances of REM sleep, and when does it happen?
Later on in the night, 5-30 mins at a time.
Brain very active, firing as if it is highly alert and awake. DREAMS. Eye muscles - bursts of rapid activity.
REM Sleep Behavioural Disorders what happens?
Lacking the inhibitory projections from the pons to the spinal chord, so when in REM sleep will act out dreams.
Where i the inhibition occuring in REM Sleep to prevent acting out dreams?
Between the pons and the spinal chord
What pathway is REM sleep dependant of?
Cholinergic pathways in the reticular formation (so anticholinesterases increase the time spent in REM sleep)
What happens if you are deprived in REM sleep
You will catch up on subsequent nights
What happens to our REM sleep as we get older?
It decreases, possibly due to cognitive decline. As it is associated with maybe making new neuronal connections it could mean that less new neuronal connections are being made
What is insomnia?
chronic inability to obtain the necessary amount or quality of sleep to maintain adequate daytime behaviour”, very subjective, very common.
primary vs secondary insomnia
Primary is chronic - no identifiable cause
Secondary = temporary due to pain, bereavement or other crisis, usually short lived.
How to treat insomina?
Usually nowadays with proper sleep hygiene! (no eating, exercise or screen/visual stimulus before bed)
