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NSB! > Physiology of sleep > Flashcards

Physiology of sleep Flashcards

1
Q

What is sleep?

A
  • a naturally recurring state of mind and body
  • characterised by altered consciousness, relatively inhibited sensory activity, reduced muscle activity and inhibition of nearly all voluntary muscles during rapid eye movement (REM) sleep
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2
Q

We need to measure sleep. What is a qualitative approach to measuring sleep?

A
  • questionnaires
  • simple and cheap
  • increased bias as patients may falsify data
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3
Q

We need to measure sleep. What are the 4 most common quantitative physiological measurements to measuring sleep?

A
  • brain wave activity (EEG)
  • neurochemicals (saliva, blood)
  • sleep models
  • pharmacology
  • free from bias as patient and clinician have no control over them
  • results are repeatable
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4
Q

What is an Electroencephalography (EEG)?

1 - recording of the number of eye twitches
2 - recording of individual brain neurons during sleep
3 - collective brain activity during sleep
4 - average recording of brain areas during sleep

A

4 - average recording of brain areas during sleep
- recording of a gross average of electrical potentials of the cells and fibres
- brain areas closest to each electrode attached to the scalp provide the information

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5
Q

In an EEG, how are the signals created?

1 - electrodes are able to penetrate the skull into the brain
2 - electrodes send an electrical current that rebounds creating a signal
3 - electrodes detect action potentials from neurons in the brain
4 - electrodes detect physical movement attributed to neuronal activity

A

3 - electrodes detect action potentials from neurons in the brain

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6
Q

Why does the organisation of the detectors on an EEG need to be aligned in a parallel manner?

1 - waves of activity are detected strongest in this alignment
2 - waves do not cancel each other out in this alignment
3 - waves are able to pinpoint individual neurons using this alignment

A

2 - waves do not cancel each other out in this alignment
- neurons cells have to synchronise to generate electrical signal, if not the positive and negatives can cancel each other out

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7
Q

Parts of the brain are able to stimulate synchronised action potentials in the absence of a stimulus, such as the thalamus. How does the thalamus achieve this?

1 - thalamus has its own circuits so is not under control of the cortex
2 - thalamus is able to lower action potential threshold
3 - thalamus receives stimulus from other areas of the brain despite no stimulus

A

2 - thalamus is able to lower action potential threshold
- lower resting membrane potential allows action potentials to be achieved easier

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8
Q

Parts of the brain are able to stimulate synchronised action potentials in the absence of a stimulus, such as the thalamus. The thalamus contains a set of voltage-gated ion channels that are able to lower resting membrane potential (-70 to 50) by controlling the ions that pass through, making it easier for an action potential to occur. What are 2 channels that certain parts of the brain can modulate, such as the thalamus to facilitate synchronised action potentials in the absence of a stimulus?

1 - K+ and Ca2+ entering the cell
2 - K+ and Ca2+ leaving the cell
3 - K+ entering the and Ca2+ leaking into the cell

A

3 - K+ entering the and Ca2+ leaking into the cell
- if this happens in multiple cells we get synchronisation

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9
Q

In addition to a reduction in K+ re-entering the cell and having Ca2+ leak channels that facilitate synchronisation of action potentials in multiple cells, what else can over ride this and cause a synchronised action potential?

A
  • a stimulus where an action potential is delivered to parts of the brain
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10
Q

The EEG can be used to determine what stage of sleep a patient is in. How many stages of sleep are there?

1 - 2
2 - 4
3 - 5
4 - 7

A

3 - 5

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11
Q

There are 4 stages of sleep. Using the labels below label the image:

  • non rapid eye movement, now = N1
  • non rapid eye movement, now = N2
  • stage 3 and 4 was was non rapid eye movement, now = N3
  • rapid eye movement
A

1 - stage 1, was non rapid eye movement, now = N1
2 - stage 2, was non rapid eye movement (NREM), now = N2
3 - stage 3 and 4 was was non rapid eye movement (NREM), now = N3
4 - Rapid eye movement (REM)

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12
Q

The EEG can be used to determine what stage of sleep a patient is in. There are 4 stages of sleep, when does this normally occur and what can we see on the EEG?

1 - stage 1, was non rapid eye movement, now = N1
2 - stage 2, was non rapid eye movement (NREM), now = N2
3 - stage 3 and 4 was was non rapid eye movement (NREM), now = N3
4 - Rapid eye movement (REM)

A
  • immediately after falling asleep
  • brain activity begins to decline
  • irregular wave forms with low voltage theta waves
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13
Q

The EEG can be used to determine what stage of sleep a patient is in. There are 4 stages of sleep, when does this occur and what can we see on the EEG in stage 2?

1 - stage 1, was non rapid eye movement, now = N1
2 - stage 2, was non rapid eye movement (NREM), now = N2
3 - stage 3 and 4 was was non rapid eye movement (NREM), now = N3
4 - Rapid eye movement (REM)

A
  • occurs within 30-45 minutes of asleep
  • sleep spindles are common (cells in thalamus and cortex interacting)
  • K-complex may be present (suppressing cortical activity)
  • theta waves present
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14
Q

The EEG can be used to determine what stage of sleep a patient is in. There are 4 stages of sleep, what can we see on the EEG in sleep stage 3 (NREM N3)?

1 - stage 1, was non rapid eye movement, now = N1
2 - stage 2, was non rapid eye movement (NREM), now = N2
3 - stage 3 and 4 was was non rapid eye movement (NREM), now = N3
4 - Rapid eye movement (REM)

A
  • transition between deep and light sleep
  • delta waves are present
  • slow, large amplitude waves.
  • neural activity is highly synchronised.
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15
Q

The EEG can be used to determine what stage of sleep a patient is in. There are 4 stages of sleep, what can we see on the EEG in sleep stage 3 (NREM N4)?

1 - stage 1, was non rapid eye movement, now = N1
2 - stage 2, was non rapid eye movement (NREM), now = N2
3 - stage 3 and 4 was was non rapid eye movement (NREM), now = N3
4 - Rapid eye movement (REM)

A
  • increased delta waves
  • N3 and N4 are often referred to as slow wave sleep
  • nightmares, bed wetting and sleep walking generally occur here
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16
Q

What is the deepest stage of sleep?

A
  • rapid eye movement sleep
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17
Q

When we sleep what happens to the following physiological responses?

Heart rate
Breathing rate
Brain activity

A
  • Heart rate = reduces
  • Breathing rate = slows
  • Brain activity = reduces

BUT - they can all increase during dreams

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18
Q

When we look at an EEG, what are the 2 important measurements we need to consider on an EEG trace?

A
  • amplitude (how big action potential are)
  • frequency (how often action potentials occur )
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19
Q

Label the EEG below with the following terms related to stages of sleep:

Rapid Eye Movement (REM) Sleep
Awake with eyes closed
Non-Rapid Eye Movement (NREM) Sleep.
Awake with eyes open

A

1 = awake with eyes open
2 = awake with eyes closed
3 = Non-Rapid Eye Movement (NREM) Sleep.
4 = Rapid Eye Movement (REM) Sleep

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20
Q

What is rapid eye movement (REM)?

A
  • sleep stage characterised by rapid saccadic movements of the eyes
  • brain activity is similar to stage 1 non-REM
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21
Q

The EEG below shows the stages of sleep. What is the difference between awake with eyes open and awake with eyes closed on the EEG reading?

A
  • awake with eyes open = increased stimuli so EEG is more localised depending on the activity or stimulus
  • awake with eyes closed = less stimulus as we cannot see anything so brain is synchronised with heightened senses
22
Q

The EEG below shows the stages of sleep. Here are the first 2:

  • awake with eyes open = increased stimuli so EEG is more localised depending on the activity or stimulus
  • awake with eyes closed = less stimulus as we cannot see anything so brain is synchronised with heightened senses

However, why is the frequency and amplitude higher when the patients eyes are closed?

A
  • frequency and amplitude is higher when eyes are closed
  • action potentials = (K+ and Ca2+ channels) become synchronised as less stimulus
23
Q

When we move from awake eyes closed to non-rapid eye movement, what happens to the frequency and amplitude of the EEG?

A
  • brain waves become more synchronised
  • amplitude will begin to increase
24
Q

In rapid eye movement, what happens to the frequency and amplitude of the EEG?

A
  • amplitude decreases
  • frequency increases
25
Q

Alpha and beta waves dominate when we are awake. What are their characteristics?

A
  • beta = highest frequency and lowest amplitude (busy mind)
  • alpha = lower frequency than beta waves
26
Q

As we enter stage 1 (N1) of sleep what is the dominant wave style?

A
  • more synchronised wave forms
  • lots of brain activity is maintained
27
Q

As we enter stage 2 (N2) of sleep what is the dominant wave style?

A
  • sleep spindles and K-complex
  • brain synchronisation is increased
  • amplitude is increased and frequency is decreased
28
Q

During stage 2 (N2) of sleep we can see K-complexes, what are they?

A
  • suppress cortical arousal as there has been auditory stimulus
  • brains response to stimuli that the sleeping brain evaluates not to signal danger
  • second, aiding sleep-based memory consolidation
29
Q

During stage 2 (N2) of sleep we can see sleep spindles, what are they?

A
  • a rapid burst of oscillatory activity
  • due to synchronised neural activity between the thalamic reticular nuclei and other areas of the thalamus
30
Q

As we enter stage 3 (N3) of sleep what is the dominant wave style?

A
  • delta waves
  • characterised by large amplitude and low frequency waves
  • signals high synchronisation
31
Q

As we enter stage 4 (N3), also known as slow sleep, delta waves are the dominant wave form. What can actually happen during this time if someone is asleep?

A
  • bed wettings, sleep walking, nightmares
  • increased wave amplitude occurs
32
Q

Stages 3 and 4 (N3) are known as the non rapid eye movement stages, what else are they known as?

A
  • slow wave sleep (SWS)
33
Q

As we enter the transition between N3 (non-rapid eye movements/slow wave sleep) and rapid eye movement of sleep what happens the the depth of our sleep?

A
  • we enter a lighter sleep followed by a deep sleep
  • children find this difficult
  • REM is the deepest sleep
34
Q

As we enter the rapid eye movement of sleep what can we expect to see on the EEG?

A
  • irregular, low amplitude and high frequencies (similar to stage 1)
  • dreaming occurs, as the brain thinks this is happening
35
Q

During rapid eye movement sleep we can have some physiological changes. What happens to the following:

Postural muscles
Heart rate
Blood pressure
Breathing rate
Blood supply

A
  • Postural muscles = more relaxed
  • Heart rate = variable depending on the dream
  • Blood pressure = variable depending on the dream
  • Breathing rate = variable depending on the dream
  • Blood supply = increases to reproductive organs

Increased blood supply to reproductive organs (e.g. penile erections in males).

36
Q

How long does a regular sleep cycle last?

1 - 30-45 minutes
2 - 30-60 minutes
3 - 90-120 minutes
4 - 120-180 minutes

A

3 - 90-120 minutes

37
Q

In our 1st cycle of sleep when we go to sleep do we proceed in a logical linear fashion from stage 1 (N1), through N2, N3 to rapid eye movement sleep?

A
  • yes
38
Q

During a regular sleep cycle we proceed from stage 1 (N1) to rapid eye movement (REM) sleep, moving through N2, and N3. Do we just stage in REM stage of sleep then until we wake up?

A
  • no
  • start at stage 2 (N2), to N3 and through to REM sleep
  • this repeats every 90-110 minutes
39
Q

Benzodiazepines are a class of psychoactive drugs that are generally used for sedation and hypnotics (depressants). These drugs lower brain activity, and can therefore also be used to help people sleep. How do they reduce brain activity and help with sleep?

1 - inhibit Na+ channels from opening
2 - inhibit Ca2+ channels from opening
3 - act as a GABA agonist allowing Cl- to flow into cells
4 - act as a dopamine agonist

A

3 - act as a GABA agonist allowing Cl- to flow into cells
- increased intracellular Cl- means no depolarisation and reduced neuronal activity
- diazepam our core drug

40
Q

Benzodiazepines are a class of psychoactive drugs that are generally used for sedation and hypnotics by reducing neuronal activity. These drugs lower brain activity, and can therefore also be used to help people sleep. Diazepam is our core drug and acts as a GABA agonist. What is the negative side effect of taking Benzodiazepines as a sleeping aid?

1 - prolonged sleep cycle length so we wake up feeling more tired
2 - eliminates stages N2 and N3 so brain turns off quicker which is detrimental
3 - reduces N2, N3 and REM stages of sleep
4 - difficult to wake up

A

3 - reduces N2, N3 and REM stages of sleep
- REM is important for feeling refreshed following sleep

41
Q

Benzodiazepines are a class of psychoactive drugs that are generally used depressants. These drugs lower brain activity, and can therefore also be used to help people sleep. Diazepam is our core drug and acts as a GABA agonist. What effect do Benzodiazepines have on the sleep stages?

A
  • stages 1 and 2 = increases length of stage
  • stages 3 and 4 = decreases length of stage
  • rapid eye movement sleep = decreases length of stage
42
Q

When we sleep, which stage is the most important to us waking up feeling refreshed?

A
  • rapid eye movement sleep
  • more cycles = more refreshed
43
Q

EEG is commonly used to measure brain activity, but what are some common limitations to EEG?

A
  • not sensitive to pick up individual action potentials
  • cannot distinguish between excitatory, inhibitory or modulatory
  • limited anatomical anatomy (fMRI is better)
44
Q

What are the 2 major hormones that regulate sleep-wake activity are what?

1 - prolactin and cortisol
2 - cortisol and testosterone
3 - cortisol and melatonin
4 - cortisol and adrenaline

A

3 - cortisol and melatonin
- cortisol (peak early am 7-9am)
- melatonin (peak late pm 9pm-3am)

45
Q

The 2 major hormones that regulate sleep-wake activity are cortisol (peak early am 7-9am) and melatonin (peak late pm 9pm-3am). What happens to the levels of one another throughout the day?

A
  • if cortisol increases melatonin decreases
  • if cortisol decreases melatonin increases
46
Q

Circadian rhythms are physical, mental, and behavioural changes that follow a 24-hour cycle. These natural processes respond primarily to light and dark and affect most living things. What happens to cortisol levels during circadian rhythms?

A
  • cycles
  • peaks once light begins
  • able to maintain this cycle even without light, our circadian clock
47
Q

The pacemaker of the circadian clock is located in the brain controlling the whole body. Specifically what part of the brain is referred to as the central circadian pacemaker?

1 - ventral tegmental area
2 - nucleus accumbens
3 - suprachiasmic nucleus
4 - hypothalamus

A

3 - suprachiasmic nucleus
- circadian clock is messed up with jet lag (takes few days to re-regulate)

48
Q

What are parasomnias?

A
  • disruptive sleep-related disorders
  • can cause abnormal movements, talk, emotions and actions while you’re sleeping although your bed partner might think you’re awake.
49
Q

Parasomnias are disruptive sleep-related disorders, that can cause abnormal movements and actions when we are asleep. They can be grouped into non-rapid eye movements (NREM) and rapid eye movements (REM). What happens in these 2 groups?

A
  • NREM Parasomnias:
    1 - Sleepwalking, but still exhibit limited awareness or responsiveness to their surroundings
    2 - Night Terrors, scream in their sleep, but not responsive to outside stimuli and will have no recollection of the source for their terror upon waking
  • REM Parasomnias
    1 - unusual vocalisations or movements during REM sleep, often as a reaction to a dream
50
Q

In sleep stages what is the deepest and lightest stages of sleep?

Stage 1 NREM N1 1-5 minutes
Stage 2 NREM N2 10-60 minutes
Stage 3 NREM N3, Slow-Wave Sleep (SWS), Delta Sleep, Deep Sleep 20-40 minutes
Stage 4 REM REM Sleep 10-60 minutes

A
  • deepest = REM
  • lightest = Stage N1
51
Q

What are the 3 main limitations to EEG?

A
  • electrodes unable to detect individual action potentials
  • electrodes unable to distinguish between excitatory, modulatory or inhibitory activity
  • limited anatomical specificity compared with other imaging tool such as fMRI

NSB! (53 decks)

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