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PSYCHOBIOLOGY > 8 - SLEEP WAKE CYCLE > Flashcards

8 - SLEEP WAKE CYCLE Flashcards

1
Q

several biological systems co-vary with the sleep wake cycle

(3)

A
  • sugar
  • insulin
  • cortisol
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2
Q

what happens if you have sugar before bed?

A
  • blood sugar levels rise
  • insulin levels rise
  • blood sugar levels drop
  • cortisol increases (to make new sugar - but can’t keep producing cortisol due to negative feedback loop)
  • sleep cycle is disrupted
  • someone who struggles to sleep could be because of eating before bed (not due to mental health)
  • metabolism decreases with age - so sugar has a larger effect on the sleep cycle
  • sugary snack = higher insulin so higher cortisol = disrupts sleep
  • suggest not eating sugary snack after middday
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3
Q

why does cortisol increase when we’re about to wake up?

A
  • stress response to kick body into action

- cortisol lowest when we’re about to go to sleep = calm for sleeping

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4
Q

how is cortisol released?

A

hypothalamus CRH > pituitary ACTH > adrenal gland cortisol

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5
Q

why is cortisol released?

A
  • in response to STRESS or LOW BLOOD SUGAR
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6
Q

what is the function of cortisol?

2

A

1 - gluconeogenesis = “sugar-new-making”
- sugar from scratch, things other than from glycogen or fatty acids

2 - immune suppression

further effects

  • increases blood pressure (eg stress)
  • inhibits CRH (corticotropin releasing hormone)(negative feedback loop)
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7
Q

what are cycles controlled by?

2

A

1 - internally generated (endogenous) ‘biological clocks’ (one or more)

2 - external cues (‘zeitgeber’) reset biological clocks (eg change between day and night)

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8
Q

what happens if there is no zeitgeber?

A
  • sleep-wake cycle moves
    = FREE RUN of internally generated rhythm
  • can be 23/24/25 hours etc
  • usually still sleep the same amount and still have a regular pattern, the cycle just shifts
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9
Q

how does a zeitgeber affect sleep

A
  • cycle matches the environment
  • reset biologically clocks every day
  • can be any form of external cues such as food delivery etc
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10
Q

how active is the brain in REM sleep?

A
  • sleeping brain is typically less active
  • but MORE ACTIVE IN REM SLEEP
  • electrical and metabolic brain activity almost like waking state
  • most vivid dreaming (detailed and story like)
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11
Q

what is hertz (Hz)

A
  • waves past a certain point per second
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12
Q

what are the sleep stages characterised by?

A
  • specific bodily states
  • specific electrical brain activity
  • specific muscle activity
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13
Q

what are metabolic and electrical activity like during the sleep stages?

A

wakefulness = high

non REM sleep = reduced

REM sleep = high

= multistage process

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14
Q

electrical brain activity in the sleep stages

A 
awake = beta (>13Hz) (alert peak)
awake = alpha (8-13Hz)

stage 1 drowsy = theta and alpha (3-7Hz)

stage 2 light sleep = sleep spindles (high frequency clump - 12-14Hz) and K-complexes (really high amplitude)

stage 3 = waves get longer and slower

stage 4 deep sleep (SWS) = delta (0.5-2Hz) large

REM = beta (>13Hz) and sawtooth waves (slightly higher)

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15
Q

skeletal muscle activity during the sleep stages

A

awake (active) = beta
awake (relaxed) = alpha

over the stages (1-4)

  • EEG synchronises
  • heart rate slows down
  • EMG (electromyogram) = little muscle activity
  • EOG (electroculargram) = little eye movement
REM 
- EEG desynchronises (like beta)
- no muscle activity
- rapid eye movements
- heart rate speeds up 
PARADOXICAL SLEEP = dreaming
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16
Q

what is paradoxical sleep

A
  • body held in paralysis
  • brain activity resembles waking state
  • sleep stage with the move vivid dreams
17
Q

what is there no muscle activity in REM?

REM atonia

A
  • could be defensive to prevent us from acting out our dreams
  • nuclei in the pons and medulla actively paralyse the body by lowering muscle tone of skeletal muscles
18
Q

information:

same sleep pattern in mice and humans

A

-

19
Q

psychoanalytical interpretation of negative dreams

A
  • subconscious mind = battle ground
  • we want something forbidden but we know it’s forbidden so we hide it from ourselves and punish ourselves for wanting it
  • hence causes negative feelings
20
Q

psychobiological interpretation of negative dreams

A
  • subconscious mind perceives the body as immobilised and helpless
  • which we are in REM sleep (paralysed)
  • potentially dangerous as were vulnerable to predators
21
Q

systematic progression in the sleep stages

A
  • during sleep, REM and non REM stages alternate
  • time spent in each phase changes systematically
  • more time spent in deep sleep (stages 3 and 4) in the first half of the night
  • more time spent in REM and light sleep in the second half of the night
  • week 8, pg 5 for diagram*
  • REM = red
  • stage 4 (SWS) = dark brown
  • light sleep = orange
22
Q

life span changes of sleep patterns

A

infancy

  • more than half of sleep is REM
  • REM and overall sleep decreases with age
  • early infancy = sleep around 16 hours a day

childhood

  • sleep around 12 hours a day
  • mainly SWS

adolescence/adulthood

  • teenager = same REM as adult
  • SWS decreases
  • REM constant from 5
23
Q

sleep wake cycle in infant

A
  • don’t sleep constantly

- in and out of sleep all day

24
Q

sleep wake cycle in childhood

A
  • a couple of naps during the day

- sleep during the night

25
Q

sleep wake cycle in adults

A
  • sleep around 8 hours at night
26
Q

sleep stages in childhood

A
  • children have higher SWS

- each episode lasts longer

27
Q

elderly sleep stages

A
  • wake up repeatedly

- struggle to get into REM sleep

28
Q

animal studies into sleep deprivation

A 
- initially decrease in 
body temp 
metabolism 
appetite
(saving energy?)
  • subsequently
    failure to immune system
    loss of resistance to infection
    death

could be due to the stress of being kept awake and not due to lack of sleep?

29
Q

human sleep deprivation

A
  • results in impaired physical and cognitive function
  • impaired speech
  • impaired memory
  • hallucinations

= asleep on your feet

  • large inter-individual variety
  • most people need approx 8 hours
  • but some can function on less than 4 hours
30
Q

REM rebound

A

after sleep deprivation - body will try to ‘catch up’ on missed sleep
- can be selective - miss out on REM sleep - next nights sleep will catch up and include more REM sleep

31
Q

evolutionary perspective to sleep

the paradox of sleep

A
  • sleep is dangerous = vulnerable
  • but all animals with breaking show some form of sleep (even insects have periods of rest)
  • in higher animals, sleep is controlled by a complicated system of interacting neuro-endocrine functions
  • therefore there must be some advantage to sleep
  • don’t know fully what it is yet (but DNA repair could be one - don’t know if we need sleep to do repairs or if they just repair when asleep)
32
Q

information:

some animals have developed a method to stay away when sleeping

  • dolphins
  • one hemisphere sleeps whilst the other has beta activity
  • vital in marine mammals
  • need to go to surface for air
A

-

33
Q

REM and memory consolidation

A
  • higher levels of Ach in REM

- and known to be involved in memory

34
Q

hormones with a circadian rhythm

A
  • cortisol
  • growth hormones
  • testosterone - peak around midday and lowest around midnight in males
  • also in women, but shallower peaks etc
35
Q

which rhythm does progesterone have

A
  • infradian

- menstrual cycle

36
Q

what is a sleep spindle?

A
  • high frequency wave cluster in stage 2 sleep
  • periodic bursts of activity around 12-14Hz and last around 1-2 seconds
  • due to interaction of thalamic and cortical neurons

PINK PATCH ON DIAGRAM - closer together frequency

PSYCHOBIOLOGY (29 decks)

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