Sleep Flashcards

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1
Q

What is sleep?

A

A periodic, natural, reversible behavioural state of perceptual disengagement from and unresponsiveness to the environment.

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2
Q

What is sleep characterised by?

A
  • Sustained immobility or inactivity
  • characteristic posture
  • reduced responsivity to external stimuli
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3
Q

How is sleep different from anaesthetic and being in a coma?

A

Sleep is easily reversible.

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4
Q

How do dolphins engage in sleep and how does this relate to the immobility characteristic?

A

They engage in uni-hemisphere sleep which allows them to still get up to surface to get water and shows that we can sleep without being completely immobile.

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5
Q

How does characteristic posture of sleep vary?

A

It depends on whether the anima is prey or predator - prey will sleep in a position where it is easy to get up and away to avoid danger whereas predators like humans can sleep easily laying down as they do not have this threat.

Also it depends on the anatomy of the animal as animals like horses find it hard to get down onto the floor and get back up again so it is easier for them to sleep standing up.

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6
Q

How does reduced responsivity during sleep vary?

A

Adults are more easily awaken than children as they need to listen out to children crying and look after them, but also it depends on individual differences, some people are naturally heavy sleepers whilst others aren’t.

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7
Q

Why do we sleep according to Moruzzi, 1972?

A

Restoration - being awake disrupts homeostasis and being asleep restores this. Clearance of toxic waste products is also twice as fast during sleep, and slow oscillations mean it is a short period of rest for neurons.

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8
Q

Why do we sleep according to Seigel, 2009?

A

Adaptation - sleep follows our evolution, we don’t see well at night which means we are most vulnerable at this time so sleep evolved to prevent accidents and predation at night. Also, sleep saves energy that we can use during the day and allows awakening when needed.

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9
Q

Throughout species what causes and do not cause differences in sleep duration?

A

Not causes:
- Size of animal
- Exercise/ activity eg. sloths sleep 20h p/d but barely move whereas horses run a lot and only need 3
. however they may be a little increase in humans

Are causes:
- Species with high metabolic demands sleep more for example horses eat straw which requires a long time to digest which they cannot do whilst asleep

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10
Q

What determines whether we are a night owl or early bird?

A

It all depends on our chronotype

  • In general the older you get the earlier you wake up - our chronotype shifts over our lifetime
  • Can be determined by genes - 40-60% of variants of chronotype depend on genes (length of the per3 gene and whether it is 4 or 5 repeats predicts dinural preference)
  • Once again is just due to individual difference in a lot of cases
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11
Q

What is social jet lag?

A

When you have to wake up out of your circadian rhythm and you have a sleep deficit eg. if you are a night owl but work requires you to be up at 6am every day, you will encounter social jet lag.

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12
Q

What effects do you encounter with sleep deprivation (in the case of Randy Gardner, 1965)?

A
  • Irritable
  • Nauseated
  • Memory problems
  • Mild delusions
  • Overwhelming fatigue
  • Tremors
  • Language problems
  • Mood
  • Reduced attention
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13
Q

How long does it take to recover from sleep deprivation?

A

You can normalise very quickly and return to original sleep patterns after a day or two, which show restoration theories to not be as true as originally thought because you would expect a lot longer recovery period. This is not true for some animals deprived of sleep however.

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14
Q

What evidence does sleep deprivation have for restoration theory?

A

If you work several night shifts in a row then you end up with sleep deficits, they accumulate over time.

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15
Q

What do we mean when we say sleep is multifactorial?

A

No single theory of sleep is completely satisfactory. It originally served to keep us quiet and still at night but now other functions that work best when we are quiet and still have piggy backed on to it.

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16
Q

How can we measure sleep?

A
  • Patient reported outcomes eg. sleep diaries and questionnaires
  • Actigraphy eg. recording motor activity during sleep
  • Polysomnography (PSG)
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17
Q

Why is actigraphy not completely reliable as a measure of sleep?

A

Activity varies a lot within sleep eg. people who sleep walk or even just turning over.

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18
Q

How does PSG work?

A

It uses an EEG to measure brain activity, EMG to measure muscle activation - particularly facial muscles, and an EOG to measure eye movements.

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19
Q

What do delta waves show on an EEG?

A

Slow and deep sleep

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20
Q

What do theta waves show on an EEG?

A

Drowsy - can occur both during sleep and wake

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21
Q

What do alpha waves show on an EEG?

A

Relaxed wakefulness

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22
Q

What do beta/gamma waves show on an EEG?

A

Awake, alert, and excited

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23
Q

In order of increased amplitude, what are the different EEG rhythms?

A
  • Beta/gamma
  • Alpha
  • Theta
  • Delta
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24
Q

In order of increased frequency, what are the different EEG rhythms?

A
  • Delta
  • Theta
  • Alpha
  • Beta/Gamma
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25
Q

What are spindles and ripples in EEG rhythms?

A

These occur in light sleep and are linked to memory consolidation

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26
Q

Which stage does REM sleep occur in?

A

Stage 1, this lengthens the longer you sleep

27
Q

What is the deepest form of sleep?

A

Stage 4

28
Q

What is the lightest form of sleep?

A

Stage 1

29
Q

What brain activity is there during REM sleep?

A

Increased activity in the striatal cortex which means there are more dreams, however the pre frontal cortex is inhibited which is why you have a lack of control over the content of your dreams. There is also an inhibition of motor activity during REM sleep which stops us acting out what is happening.

30
Q

What is the difference in EEG between slow wave and REM/Paradoxical sleep?

A

Slow wave - Large amplitude

REM - Low amplitude - similar to waking

31
Q

What is the difference in the body between slow wave and REM/Paradoxical sleep?

A

Slow wave - temperature drop and heart rate slows

REM - core temperature drops and heart rate and respiration increases

32
Q

What is the difference in spinal reflexes between slow wave and REM/Paradoxical sleep?

A

Slow wave - some reduction but it is capable of movement

REM - strong descending inhibition of motor neurons.

33
Q

What is the difference in arousal between slow wave and REM/Paradoxical sleep?

A

slow wave -arousal only to REM - significant stimuli

raised threshold but often waking from REM

34
Q

What is the difference in phasic sleep between slow wave and REM/Paradoxical sleep?

A

Slow wave - muscle twitches
REM - Sudden eye movements
Both have sudden CNS discharges

35
Q

What is the difference in reports on waking between slow wave and REM/Paradoxical sleep?

A

Slow wave - dreams - 0-20%

REM - dreams - 80-90%

36
Q

What does the reticular formation do?

A

It regulates sensory information via the thalamus through the rest of the cortex

37
Q

What is the relationship between cortisol and sleep?

A

Cortisol is the hormone that wakes us up, it oscillates throughout the day and peaks just before you wake up. People with raised cortisol therefor have trouble sleeping (this is bidirectional however as it may be that people who have trouble sleeping have raised cortisol).

38
Q

What is the relationship between melatonin and sleep?

A

This is the reverse to cortisol - it prepares you for darkness behaviour such as sleep. The biological clock drives melatonin rhythm as it responds to light coming into your body through your eyes and regulates melatonin level. This is made in the pineal gland, and it is not found to be associated with meals, stress, bathing, just light. Levels of melatonin peak in the middle of the night and are at the lowest when you wake up.

39
Q

What 3 neurotransmitters promote arousal?

A
  • Noradrenaline
  • Serotonin
  • Acetylcholine
40
Q

How do neurotransmitters promote sleep?

A

Adenosine - Inhibit systems that promote wakefulness. Levels progressively increase during prolonged walking and decrease during sleep.

GABA - decrease firing rate of most brain stem modulatory neurons

Dopamine - modulates REM sleep rather than promoting sleep itself, it contributes towards dream generation.

41
Q

What are some of the factors that cause you to go to sleep?

A
  • Increase in GABAergic activity in the cortex
  • Deactivation of the locus coeruleus which is where noradrenaline is stored.
  • Less activity of reticular activating system
  • Reduced histamine and orexin in the hypothalamus
  • Increased melatonin in the pineal gland
42
Q

What are the main sleep disorder categories?

A
  • Insomnias
  • Hyper somnolence - eg. narcolepsy (daytime sleeping)
  • Parasomnias eg. sleep walking (sleep disruptive disorders)
  • Circadian rhythm disorders (timing of sleep)
  • Breathing disorders eg. sleep apnea
43
Q

What are the causes of insomnia?

A
  • Overactive thyroid
  • Poor mental or physical health
  • Medication
  • Stress
  • Environmental factors

This is one of the most common sleep disorders, acute insomnia lasts a few days in a row whereas chronic insomnia is usually due to stress and environmental factors.

44
Q

What are some examples of parasomnias?

A
  • Sleep walking
  • Night terrors
  • Restless leg syndrome
  • Periodic limb movements
  • Sexsomnia
  • Sleep-related eating disorder
  • REM sleep behaviour disorder
45
Q

What is REM sleep behaviour disorder?

A

Sleep paralysis is absent due to lesions in the pons near the reticular so motor behaviour is no longer inhibited and patients will become aggressive during their sleep. Most patients are male and it is often related to Parkinson’s disease.

Treatment for REMSBD is with benzodiazepines or melatonin.

46
Q

What are the causes of sleep apnea?

A
  • Commonly associated with weight
  • Lifestyle choices: smoking, alcohol, medicines
  • Having a large neck or unusual neck structure
  • Has a correlation with age (40+), gender (male), and the menopause
47
Q

How does sleep apnea work?

A

Muscles and soft tissues in the throat relax and collapse, obstructing airways, meaning oxygen levels drop in the blood so you wake up to resume breathing. People with this disorder will often fall asleep during the day as they never reach deep sleep during the night, and often don’t remember awakenings.

48
Q

What are circadian rhythm disorders?

A

These are intrinsic and not caused by shift work etc, it is an altered or disrupted sensitivity to external cues. Has been seen in blind people, ADHD, depression, or neurogenerative diseases. Treatment for these disorders involves light exposure or melatonin.

49
Q

What is the dual process model of sleep?

A
  1. Sleep-wake homeostasis - accumulation of hypnogenic substances in the brain
  2. Circadian rhythms - regulates the body’s internal processes and alertness.
50
Q

What are zeitgebers and how do they facilitate sleep?

A

These are external cues that help entrain the day night rhythm and regulate our internal clock.

51
Q

What are ganglion cells?

A

Large nonselective receptive fields responding to luminance. It is a photoreceptor that is excited by light and sends signal to the suprachiasmatic nuclei (SCN).

52
Q

What is jet lag?

A

A mismatch between external and internal clocks

53
Q

What are consequences of jet lag?

A
  • Elevates cortisol
  • Fatigue (due to melatonin disruption)
  • Loss of concentration
  • Change in appetite (ghrelin)
  • Body temperature fluctuations
54
Q

What is the best way to combat jet lag?

A
  • Restrict light exposure, meals, and activity

- Take a supplement of melatonin

55
Q

Why do we dream?

A
  • Wish fulfilment (Freud - this is unlikely) - unconscious way to express aggressive and sexual fantasies
  • Physiological function theory - promotes neural development and preserves neural pathways by providing the brain with stimulation.
  • Activation - synthesis model (Hobson and McCarley, most likely) Dream are products of brain neuro n activity in the visual cortex, memory areas and emotion areas. There is no external stimulus so the brain tries to make sense of neuron activity. The prefrontal cortex shuts down during REM so you have fewer inhibitions and don’t question illogical parts of a dream.
56
Q

What are examples of declarative learning?

A

cognitive maps, words, narratives

57
Q

What are examples of procedural memory?

A

priming, visual discrimination, motor sequences

58
Q

What confounding variables are there in sleep studies?

A
  • Time of day learning
  • Time of day testing
  • Alertness
  • Sleep deprivation, stress, and circadian basis
59
Q

What did Ebbinghaus forgetting curve show?

A

If you sleep between testing and learning you remember more.

60
Q

What did Plihal and Born do in relation to partial sleep deprivation?

A

Participants took part in a declarative and procedural memory task at different points in the day after sleeping at different points in the day.

61
Q

What did Plihal and Born find in relation to partial sleep deprivation?

A

It was seen that slow wave sleep benefits declarative memory whereas REM sleep benefits procedural memory.
Afternoon learning fosters declarative learning whereas evening learning fosters procedural memory. Also, it is better to learn new information in the morning and afternoon.

62
Q

What is targeted memory reactivation?

A

When an object is cued during sleep, then less errors will be made when tested on the object in terms of remembering the location.

63
Q

Is it good to nap?

A

Short naps improve performance but only if REM sleep is present, there are similar effects to a short nap and a whole nights sleep.

64
Q

Is it good to engage in wakeful rest?

A

Wakeful rest promotes learning but to a much smaller degree than actual sleep.