Week Nine

Question 1

Polysomnography

Answer 1

• Used to describe the set of measures used to describe and asses sleep stages.
  
  • At a minimum, three things are needed to assess sleep stages;
    ○ Electroencephalogram (EEG)= brain waves (brain, electrodes on head).
    ○ Electrooculogram (EOG)= eye movements (electrodes on eyes, temples).
    ○ Electromyogram (EMG)= muscle tension (electrodes placed on chest).

Question 2

EEG

Answer 2

• Measures electrical activity in the brain
  
  • When multiple neurons fire action potentials it can be picked up by electrodes placed on the brain.
  • Amplitude is how high or low the signal gets
  • Frequency is how long or short the wave is.

Question 3

AWAKE

Answer 3

• Beta waves are irregular (EEG when awake).
  
  • Muscle tension is high (EMG awake)
  • When deciding to go to sleep, EEG shows moderate intensity alpha waves of intermediate frequency.

Question 4

STAGE ONE

Answer 4

○ eyes start slow rolling eye movements on EOG
○ EEG changes from alpha waves to theta waves.
○ Muscle tension is moderate
○ Usually stage one is only 10 minutes.

Question 5

STAGE TWO

Answer 5

○ EEG shows K-complexes and spindles on the theta waves.
§ Seem to be a sign of your brain compressing external information.
○ No eye movements on EOG.
○ EMG is moderate.
○ Lasts around 20 minutes

Question 6

STAGE THREE

Answer 6

○ Slow, large delta waves on EEG. 
		○ No eye movement on EOG. 
		○ Moderate EMG. 
		○ 80 minutes 
- SLOW WAVE SLEEP

Question 7

STAGE FOUR (REM)

Answer 7

○ Sawtooth waves on EEG (looks more like waking waves).
○ Bursts of eye movements
○ Low EMG
○ Stage of dreaming.

Question 8

NREM Sleep

Answer 8

• Stages one to three are often known as NREM sleep.

- In NREM sleep, blood pressure comes down, then goes up in REM.

Question 9

Pons

Answer 9

• Pons is essential to REM sleep.
  
  • During sleep, pons sends two types of signals
    ○ First is up to the thalamus and the cortex, an activating signal. This is associated with dreams
    ○ Second is towards the spinal cord and is a deactivating signal.

Question 10

dreams

Answer 10

• We usually remember dreams from our last REM cycle.
  
  • More likely to remember longer dreams, those with emotional intensity and ones towards the end of the night.
  • REM dreams are weird and unconventional.
  • NREM dreams are more similar to everyday life, can be thoughts etc.

Question 11

sleep is…

Answer 11

homeostatic and circadian

Question 12

homeostatic

Answer 12

• Homeostatic refers to the fact that the longer we are awake the more we need sleep. Also known as Process S.
  
  • Adenosine is a neurotransmitter that is increased the longer we are awake.
  • Caffeine blocks adenosine receptors.

Question 13

circadian

Answer 13

• Without external input, out body still revolves around a 24 hour cycle.
  
  • Circadian rhythms are behavioural, biochemical and physiological fluctuations occurring over a 24 hour period.
    ○ Sleep/wake cycle is influenced by internal clock.
    ○ Suprachiasmatic nucleus (SCN) located in the hypothalamus and contains our internal clock.
    ○ Our internal clock is generally longer than 24 hours
    ○ We have mechanisms for synchronising this clock with the outside world.
  • Light is our primary zeitgeber (time giver).
  • Retinohypothalamic tract deals with light.

Question 14

jetlag

Answer 14

• Occurs when crossing a number of time zones
  
  • Results in a mismatch between our internal clock and our external day.
  • Jetlag is generally worse when travelling east as you are trying to shift your sleep period earlier.

Question 15

sleep deprivation

Answer 15

• More likely to fall asleep
  
  • PDT, press a button when the red dot appears on the screen.
  • In sleep deprivation we see a slowed response time, a narrowing of attention and increased error.
  • Difficulty thinking flexibly and with short term memory.
  • Mood and emotion is also affected.
  • People become more risky when sleep deprived.
  • There is a large variability in response.

Question 16

sleep and memory

Answer 16

• Actively integrate new memories with pre-existing knowledge when awake.
  
  • Sleep following declarative task learning improves retention and makes it more resistant to interference.
  • Sleep can lead to ‘insight’ into previously learned information.
  • Slow wave sleep is particularly important to memory.

Question 17

characteristics of sleep

Answer 17

• Satisfaction
  
  • Alertness
  • Timing
  • Efficiency
  • Duration

Question 18

good sleep

Answer 18

• Critical for recuperation, metabolic & endocrine function.
  
  • Sleep needs to be consolidated with no interruptions.

Question 19

insomnia

Answer 19

• Can consider as symptom or disorder
  
  • Is difficulty initiating or maintaining sleep OR poor quality of sleep (at least one month).
  • Treatment with psychological and behavioural strategies (e.g. restriction of time in bed etc.)
  • Sleep state misperception
    Hyperarousal