Sleep - EEG features specifically in measurement and monitoring

Question 1

Define sleep

Answer 1

Sleep - a state of loss of reactivity to surroundings or unconsciousness which one can be aroused by sensory stimulation

Question 2

What is non REM sleep

Answer 2

deep restful sleep and is the first state progressing from alert wakefulness with corresponding changes in EEG from low voltage, high frequency alpha waves to high voltage low frequency delta waves, with increasingly synchronous patterns. Raphe nucleus secretes seratonin modulating slow wave sleep

Question 3

What area of the brain modulates slow wave sleep

Answer 3

Raphe nucleus

Question 4

What neurochemical is heavily involved in slow wave sleep

Answer 4

Seratonin

Question 5

What EEG featurs are generally seen in slow wave sleep

Answer 5

EEG from low voltage, high frequency alpha waves to high voltage low frequency delta waves, with increasingly synchronous patterns

Question 6

What are the 4 stages of slow wave sleep

Answer 6

◦ Stage 1 - lightest stage and easiest to rouse - alpha waves interspersed with lower frequency theta waves (4-6Hz)
◦ Stage 2 - 50% of normal sleep - High frequency bursts (0.5 seconds) called sleep spindles 12-14Hz and classical large slow biphasic potentials called K complexes
◦ Stage 3 - Difficult to rouse - slow 1-2Hz, high voltage delta waves with occasional sleep spindles
◦ Stage 4 - large amplitude, rhythmic slow delta waves become synchronised

Question 7

Describe stage 1 of slow wave sleep

Answer 7

◦ Stage 1 - lightest stage and easiest to rouse - alpha waves interspersed with lower frequency theta waves (4-6Hz)

Question 8

Describe stage 2 of slow wave sleep

Answer 8

◦ Stage 2 - 50% of normal sleep - High frequency bursts (0.5 seconds) called sleep spindles 12-14Hz and classical large slow biphasic potentials called K complexes
◦

Question 9

Describe stage 3 of slow wave sleep

Answer 9

Stage 3 - Difficult to rouse - slow 1-2Hz, high voltage delta waves with occasional sleep spindles

Question 10

Descrieb stage 4 of slow wave sleep

Answer 10

◦ Stage 4 - large amplitude, rhythmic slow delta waves become synchronised

Question 11

REM sleep is

Answer 11

paradoxical sleep difficult to wake from, preceeded by non REM sleep and REM is induced by noradrenaline from the locus coeruleus

Question 12

Which neuronal centre is implicated in REM sleep

Answer 12

locus coeruleus

Question 13

What neurochemical is associated with REM sleep

Answer 13

Noradrenaline

Question 14

What is the pattern of slow wave to REM sleep

Answer 14

◦ About every 90 minutes sleep lightens, heart rate and respiratory rate increase, muscle tone returns and followed by brief period of profound relaxation associated wtih rapid eye movement, and desynchronised low voltage (low amplitude), high frequency EEG +large physic waves called ponto-geniculo-occipital spikes from the pons to geniculate and Occitan regions lasting 15 minutes

Question 15

In the absence of EEG what might be some clues as to REM sleep occuring

Answer 15

◦ About every 90 minutes sleep lightens, heart rate and respiratory rate increase, muscle tone returns and followed by brief period of profound relaxation associated wtih rapid eye movement, and desynchronised low voltage (low amplitude), high frequency EEG +large physic waves called ponto-geniculo-occipital spikes from the pons to geniculate and Occitan regions lasting 15 minutes

Question 16

What EEG features help distinguish REM sleep

Answer 16

Desynchronised low voltage (low amplitude), high frequency EEG +large physic waves called ponto-geniculo-occipital spikes from the pons to geniculate and Occitan regions lasting 15 minutes

Question 17

What two phases are there to REM sleep and how do they physically appear different

Answer 17

◦ REM sleep divided into phasic and tonic phases
‣ Phasic - motor activity e.g. rapid eye movements, autonomic instability and dreaming
‣ Tonic - tonic inhibition of muscle tone

Question 18

What happens respiratory wise in non REM sleep

Answer 18

◦ Respiratory rate decreased and regular respiration —> decreased minute volume
‣ 25% reduction in minute alveolar ventilation
‣ Increased PaCO2 slightly, and reduced PaO2
◦ Reduce upper airway muscle tone - pharyngeal dilator tone reduced particularly in stage 3 non REM sleep
‣ 2x increase in airway resistance
◦ Hypoxic drive and CO2 response diminished —>mild hypercarbia and hypoxaemia

Question 19

What happens in REM sleep to the respiratory system

Answer 19

• REM sleep
  ◦ Respiratory drive further reduced + occasionally irregular leading to further minute volume and alveolar ventilation reduction
  ◦ Increased PaCO2 and reduced PaO2 with further blunting to hyper apnoeic and hypoxic regulatory responses
  ◦ Further loss of skeletal thoracic cage muscle tone and upper airway —> paradoxical breathing and upper airway obstruction

Question 20

What is consciousness

Answer 20

State of beign aware and responsive to ones surroundings

Question 21

What is the reticular formation

Answer 21

Diffuse aggreagtion of cells with a network of fibres that run in all directions in the core of the brainstem (medulla nad pons) concerned with somatic muscle control, regulation fo eye, neck, trunk and limb movements and may also received somatic, proprioceptive sensory signals as well as descneding inputs from the cerebral cortex and limbic system

Question 22

What two parts of the reticular activiting system are there anatomically - where does each project

Answer 22

Pontine - projects psilaterally down the spinal cord –> antigravity reflexes, automatic maintenance of erect posture

Medullary - axons down both sides of the spinla cord, suppresses spinal reflexes during sleep and may override spinal influences in voluntary movement via descending pathways

Question 23

Where do reticular activating descending impulses terminate

Answer 23

ventromedial group of interneurons

Question 24

What is a locus coeruleus

Answer 24

group of neurons containing norepinephrine as a NT in the pontine reticular formation

Question 25

What are the raphe nuclei

Answer 25

midline pons nuclei, send axons to excite or inhibit the thalamus

Question 26

Why is the reticular activating system important

Answer 26

modulates the pacemakers in the thalamus, influencing cortical neuronal excitabuility

Question 27

What is the gradual wave in brain wave pattern as you progress through the phases of sleep

Answer 27

shift from low voltage high frequency alpha waves to low frequency, high voltage delta waves - progression to synchronous rather than desynchronised activity

Question 28

How often does REM sleep occur

Answer 28

90 minutely

Question 29

How long does REM sleep typically last

Answer 29

15 minutes

Question 30

What effect does REM sleep have on depth of sleep, heart rate and RR

Answer 30

Sleep lightens, HR and RR increase and muscle tone briefly returns before profound relaxation of skeletal muscle and rapid eye movements

Question 31

Is REM a deep sleep or light?

Answer 31

Deep Paradoxically the EEG is similar to someone in a shalllow sleep

Question 32

Physiological changes during REM sleep

Answer 32

Dreaming Muscle done makredly decreased - snoring and airway obstruction more likely HR and RR irregular BP decreased durng tonic phase, but may increase during the phasic phase Unusual muscle contractions and bruxism in the phasic phase Brain metabolism increased by as much as 20% Glucocorticoid production increased Cerebral blood flow increases

Question 33

Where does the circadian rhythm come from

Answer 33

Suprachiasmatic nucleus of the hypothalamus receiving input from the retina, and melatonin released from the pineal gland

Question 34

Slow wave sleep neurotransmitter

Answer 34

serotonin from the raphe nucleus

Question 35

REM sleep neurotransmitter

Answer 35

Locus coeruleus releasing NA

Question 36

REM sleep EEG changes

Answer 36

Rapid, low voltage and irregular (desynchronised) EEG lrge phasic waves called pontogeniculooccopital (PGO) spikes from the pons to the geniculate body and occipital cortex

Question 37

What percentage of sleep is REM

Answer 37

15%

Question 38

Two phases of REM sleep

Answer 38

Tonic - tonic inhibition of muscles Phasic - Rapid eye movement, autonomic instabilit with irregular respiration and dreaming

Question 39

Muscle tone during sleep

Answer 39

Reduced in NREM and REM sleep - tonic inhibition in REM profound, phasic muscle contractions. Tone of upper airways reduced

Question 40

Respiratory changes in sleep

Answer 40

NREM - RR decreased and regular - 25% decrease in alveolar ventilation - Rise in PCO2 by 3-7mmHg - Decreased in PaO2 - Increase in airway resistance x 2 - Reduced muscle tone of upper airway partly to blame - HYpoxic drive and CO2 response diminished in the medullar REM - Irregular breathing - Paradoxical breathing and upper airway obstruction can occur with reduced tone - total body oxygen consumption is higher in REM than in NREM but still less than wakefullness Airway reflexes decreased Coughing impossible Laryngeal stimulation produces apnoea Mucociliary clearance reduced

Question 41

Cardiovascular changes in sleep

Answer 41

BP decreased during NREM and tonic REM; can increase in phasic RE. It is at its lowest in stage 3 and 4 of NREM sleep Cardiac output decreased in all phases of sleep HR and SVR decreased in NREM and tonic REM but icnreased in phasic REM Pulmonary vascular resisatnce increased Blood flow redistributed from the skin and muscles to splanchnic organs Transient vasoconstriction events occur during sleep - death from cardiac disorders most frequently occurs durnig sleep between 5-6am central inhibition of the baroreflex

Question 42

CNS effects of sleep

Answer 42

Cerebral oxygen consumption reduced in NREM sleep. increased above resting values in REM Cerebral blood flow normal in NREM but increases by 50% in REM sleep Increased PSNS and decreased SNS in all parts of sleep except phasic ICP increased during REM but no NREM

Question 43

Endocrine effects of sleep

Answer 43

Meltatonin from the pineal gland released due to darkness Growth hormone increased at the onset of sleep, highest during slow wave sleep. All pituitary hormones except ACTH are increased during sleep, as well as vasopressin and aldosterone increases. Cortisol decreased during the onset of sleep, and trough in earlty hours of the morning and incrteases during the second half of sleep with peak just after waking Later part of sleep insulin and glucose fall despite continous glucose Metabolic rate decreased by 15%

Question 44

Effect of sleep on temperature regulation

Answer 44

Body core temperature decreases by 0.5 degreees and shivering threshold decreased

Question 45

What is the limbic system composed of

Answer 45

Subcortical - hypothalamus, septum, hippocampus, amygdala Limbic cortex - cingulated gyrus, orbitofrontal cortex, subcallosal gyrus and parahippocampal gyrus

Question 46

What inputs does the limbic system have

Answer 46

association cortex, olfactory cortex and medial temporal obe

Question 47

Functions of the limbic system

Answer 47

Hippocampus - memory acquisition and recall, formation fo long term memory and behaviour Amygdala - emotional processing of stimuli, fear, rage and anxiety Septal nuclei - pleasure and reward Cingulate gyrs - affective aspects of events

Question 48

Draw the processing of the limbic system

Answer 48

Question 49

Effect of sleep on GIT

Answer 49

Secretion of saliva slows, swallowign is impossible oesophageal motility decreeased Increased splanchnic blood flow

Question 50

Describe the relative times in each sleep stage and the typical pattern of sleep over a night

Answer 50

Question 51

Describe the effect of sleep on relative blod flow

Answer 51

Question 52

What is K complex in the context of EEG sleep

Answer 52

N2 stage: Spindles (burst-like trains of waves in the 11- to 16-Hz range with a total duration ≥0.5 seconds) K-complexes (well-defined biphasic waves lasting ≥0.5 seconds and usually maximal over the frontal cortex)

Question 53

What is a spindle in the context of EEG and sleep

Answer 53

N2 stage: Spindles (burst-like trains of waves in the 11- to 16-Hz range with a total duration ≥0.5 seconds) K-complexes (well-defined biphasic waves lasting ≥0.5 seconds and usually maximal over the frontal cortex)

Question 54

Renal effects of sleep

Answer 54

UO decreases urinary excretion of electrolytes decreases

Question 55

Where does the inhibition come from that mediates sleep

Answer 55

Hypothalamic GABA eergic inhibition fo arousal pathways

Question 56

How does sleep and sedation compare

Answer 56

critically ill sedated patient, demonstrating that the majority of the time is maintained in N1 sleep, with microarousals every ten seconds. That doesn't sound restful. N1 stage sleep is the earliest and most shallow stage; if a person is woken from N1 stage sleep they frequently will not be able to identify the fact that they went to sleep at all.

Question 57

What is sleep

Answer 57

a state of loss of reactivity to surroundings or unconsciousness which one can be aroused by sensory stimulation

Question 58

Slow wave sleep is

Answer 58

deep restful sleep and is the first state progressing from alert wakefulness with corresponding changes in EEG

Question 59

Describe the EEG progression from awake to asleep

Answer 59

from low voltage, high frequency alpha waves to high voltage low frequency delta waves, with increasingly synchronous patterns

Question 60

Stage 1 of sleep - characteritsics? EEG features

Answer 60

◦ Stage 1 - lightest stage and easiest to rouse - alpha waves interspersed with lower frequency theta waves (4-6Hz)

Question 61

Stage 2 sleep characteristied by? What % of normal sleep? Classic findings? 2

Answer 61

◦ Stage 2 - 50% of normal sleep - High frequency bursts (0.5 seconds) called sleep spindles 12-14Hz and classical large slow biphasic potentials called K complexes

Question 62

Stage 3 sleep EEG features

Answer 62

◦ Stage 3 - Difficult to rouse - slow 1-2Hz, high voltage delta waves with occasional sleep spindles

Question 63

Stage 4 sleep? EEG features

Answer 63

◦ Stage 4 - large amplitude, rhythmic slow delta waves become synchronised

Question 64

EEG orders of wakefulness

Answer 64

Gamma Beta Alpha Theta Delta

Question 65

REM sleep - easy to wake? Induced by?

Answer 65

paradoxical sleep difficult to wake from, preceeded by non REM sleep and REM is induced by noradrenaline from the locus coeruleus

Question 66

What indicates REM sleep has started to an observer?

Answer 66

Sleep lightens, HR and RR increase, muscle tone returns briefly followed by profound relaxation and desynchronised low voltake high frequency EEG with ponto-genicuo-occipital spikes

Question 67

What is the characteritsic EEG finding to REM sleep

Answer 67

EEG with ponto-genicuo-occipital spikes

Question 68

How often does REM occur

Answer 68

90 minutely

Question 69

REM sleep phases? What charactertises each

Answer 69

◦ REM sleep divided into phasic and tonic phases ‣ Phasic - motor activity e.g. rapid eye movements, autonomic instability and dreaming ‣ Tonic - tonic inhibition of muscle tone

Question 70

Non REM sleep effect on respiratory status

Answer 70

Decreased MV due to reduction in RR 25% reduction in alveolar ventilation Increased PaCO2, and reduced PaO2 Reduced upper airwy tone and pharyngeal dilator tone, esp phase 3. 2x increase in wairway resistance Hypoxic drive and CO23 response blunted

Question 71

REM sleep effects respiratory drive how

Answer 71

◦ Respiratory drive further reduced + occasionally irregular leading to further minute volume and alveolar ventilation reduction

Question 72

What effect does REM have on gas exchange?

Answer 72

◦ Increased PaCO2 and reduced PaO2 with further blunting to hyper apnoeic and hypoxic regulatory responses

Question 73

Is upper airway obstruction more likely to occur in REM or non REM

Answer 73

REM - especially the tonic phase