Sleep and EEGS Flashcards
What is sleep and how is different from a coma
Sleep :State of unconsciousness from which an individual can be aroused via stimuli of light, touch, perception.
Coma: state of unconsciousness from which an individual CANNOT be aroused through stimuli.
What is sleeping due to?
How has this been verified?
Occurs due an inhibitory process which occurs in the pons- impulses must be send through down the mid-line of the pons (damage to this area leads to sleep deprivation)
Which are the neurotrasmitters involved in controlling sleep activity?
Serotonin and melatonin
Which impulses control sleep activity?
Neurones which are fired from the reticular formation of the midbrain
Where are the impulses from the reticular formation sent to?
- The hypothalamus
- The thalamus
- The cortex
What controls the circadian rhythm of electrical impulses
Hypothalamus and Superchiasmatic nuclei are also related to control of slee
What does circadian mean?
It defines a group of patterns in the body which change over 24 hours
What stimuli do the SCN respond to?
- Time zone changes
- Day/night
- Work patterns
Where is the SCN located?
What does this implicate?
Located just above the optic chiasma so must receive info from the brain
How does the sleep cycle work?
- Excitatory neurones are activated (from sleep centres in reticular formation) in the ascending reticular activating system (ARAS) of reticular formation
- These excitatory neurones release impulses which stimulate excitatory pathways in the CNS and PNS
- A positive feedback system allows these pathways to stay activated for a very long period of time
- These cells slowly become fatigued
- Peptides from the sleep centres oft reticular formation are released- dominate over excitatory pathways= lead to sleepiness
How do people who are blind dream?
- If bind from birth have auditory dreams
- If they become blind- they will slowly lose their ability to dream in vision
How do dolphins and birds dream?
One side of the brain awake, one asleep.
What does EEG measure
ecords electrical patterns of the brain
Measures amplitude of waves (size of wave : from 0-200 microV)
Measures frequency of waves ( measures the number of waves in 1 second 0-50)
Different EEGs based on state of consciousness
- Awake: high frequency, low amplitude
- Asleep: low frequency, high amplitude
4 types of wave seen on an EEG
Alpha
Beta
Theta Gamma
Alpha waves
High frequency, high amplitude
Wave synchronise with each so high amplitude
-Occur when alert but relaxes e.g. with eyes closed
beta waves
High frequency, low amplitude
Low amplitude a result of more waves due to more stimuli
More waves- desynchronise (opposing polarities)
-Occur when very very alert
Theta waves
Low frequency, various amplitude
-Occur in children, times of emotional stress, frustration and during sleep
Delta waves
Low frequency, low amplitude
Stages of sleep
5 stages
1-4
REM
stage 1
- Light sleep, easily aroused
- Waves have long amplitude and low frequency
- Low frequency Theta waves
- NON-REM waves
- Slow eye movements
Stage 2
- Eye movements stop
- Even slower frequency waves
- Small rapid bursts of waves = sleep spindles (12-14Hz)
Stage 3
- Very slow (2Hz)
- spindle activity decrease but where present waves are faster
Stage 4
-Only delta waves
REM sleeping
- EEG is very similar to someone who is awake- known as paradoxical
- 25% of sleep
- When dreaming occurs
Characters of deep sleep
- very very deep for the first few hours
- Decrease in vascular tone (BP), decrease in respiratory and metabolic rate
- Most restful
- Some dreams can occur but not as many as REM
Characters of REM
- Can last between 5-30 mins every 90 mins
- Becomes more frequent as hours of sleep increase
- Where most dreams occur
- Rapid movements of eye- all other skeletal muscles are inhibited by signals sent from the pons to spinal cord (prevents acting out of dreams- absent In people who suffer from REM sleep behaviour disorder)
- HR/ RR and metabolism increase- mimics waves of a person who is highly awake
- Dependant on cholinergic patheways of reticular formation to hypothalamus/thalamus and cortex. REM sleep can be increased by use of anticholerestinases
Importance of sleeping on physiology
- Lower energy available (more being used by daily activites)
- Clears waste products away from the CNS
- Neuronal plasticity
- Immune function
- Cognitive function
General importance of sleep
-Experiments show similar sleep cycle in birds and mammals- die after being deprived of sleep for 2-3 weeks When deprived: -Cognitive function impaired -Irritable -Sluggish -impaired physical performance -Psychosis in extreme cases
Sleep disorders
- Insomnia
- Nightmares
- Night terrors
- Sleep walking
- Narcolepsy
Insomnia
Definition
Types
Treatments
Defined as insufficient sleep to be able to maintain adequate daytime behaviours
Affects 33% of adults
Types:
-Primary/Chronic- idiopathic
-Secondary/ temporary- when related to pain
Treatment:
Barbituates: no longer used as chronic use showed they decrease amount of time spent in REM, stages 3 and 4, can increase amount of time it takes to fall asleep and can cause people to wake up numerous times during the night
Benzodiapenes: can cause addiction, though have less effect on REM sleep
Preferred method is to adjust sleep behavioural patterns
Cause of narcolepsy
Insufficient Orexin being released
What are night terrors
Very vivid visions in delta-sleep
Occur in 3-8 year olds
No recollection the next morning
What are nightmares
very vivid in REM sleeping
Only way yo treat is by waking them up
Somnabulism- in what stage does it occur?
Not in REM- in vert deep sleep
