sleep

Question 1

studying sleep - EMG

Answer 1

electromyography - muscle movements

Question 2

studying sleep - EOG

Answer 2

electro-oculography - eye movements (tracks muscle movements around the eye)

Question 3

studying sleep - EEG

Answer 3

electroencephalography - measures brain activity
measures synchronous electrical activity from large populations of neurons
electrical fields cased by calcium and sodium movements

Question 4

studying sleep - pros and cons of EEG

Answer 4

advantages:
non-invasive
easy to administer
easy to gather data
high temporal resolution - milliseconds

limitations:
low spatial resolution - only detects cortical activity

Question 5

types of brain waves (4 - frequencies)

Answer 5

0.5-4 Hz = delta
4-8 Hz = theta
8-13 Hz = alpha
13-30 Hz = beta

lower frequency = larger amplitude (more neurons can work synchronously

Question 6

non-REM sleep

Answer 6

low neuronal activity
low metabolic rate and brain temp
low heart rate and blood pressure (decreased sympathetic nervous system outflow)
increased action of parasympathetic nervous system
muscle tone and reflexes are intact

Question 7

5 stages of sleep

Answer 7

1 - drowsiness
2 - light sleep
3 - deep sleep
4 - very deep sleep
5 - REM sleep

Question 8

sleep stage 1

Answer 8

drowsiness
awaken easily
eyes move slowly, muscle activity slows
can have sudden muscle contractions and sensation of falling
theta waves = 4-8 Hz

Question 9

sleep stage 2

Answer 9

light sleep
no eye movement
body temp drops, heart rate slows
slower brain waves - occasional bursts of rapid waves
K complexes = slow rises and decays in voltage (more synchronous)
sleep spindles = bursts of high frequency activity (11-15 Hz) - more asynchronous

Question 10

sleep stage 3

Answer 10

deep sleep
delta waves (0.5-2 Hz) intersperse with small fast waves
sleepwalking and talking, night terrors occur in the transition from non-REM to REM sleep

Question 11

sleep stage 4

Answer 11

very deep sleep
disorientation following arousal
difficult to distinguish between stage 3+4
almost exclusively delta waves

Question 12

sleep stage 5

Answer 12

REM sleep
EEG mimics wakefulness - paradoxical sleep
eyes move rapidly side to side
low voltage, mixed frequency
rise in brain temp and metabolic rate - increased neural activity

Question 13

human sleeping pattern

Answer 13

REM and non-REM alternate cyclically
after 70-80 mins, return to stage 2/3 and then enter REM (8-10 mins)
total cycle = 90-110 minutes
4-5 times per night
stage 3+4 decrease in duration and REM increases with each repetition of the cycle

Question 14

% of sleep in different stages for young adults

Answer 14

1 = 5%
2 = 50-60%
3+4 = 20%
REM = 20-25%

Question 15

sleep regulation systems (3)

Answer 15

diffuse modulatory neurotransmission system - controls rhythmic behaviour in thalamus
NE (norepinephrine) and 5-HT (serotonin) neurons in brain stem
motor neuron inhibition

Question 16

regulation of wakefulness

Answer 16

in the brain stem
lesions to brain stem can cause sleep and comas
neuronal activation in brain stem precede awakening - depolarising effect

Question 17

brain and brain stem activity in REM vs non-REM sleep

Answer 17

non-REM = decreased brain stem firing, spindles (stage 2) and delta rhythms which are correlated with thalamus activity

REM = similar firing to awake, no frontal lobe activity or in raphe nucleus and locus coeruleus, motor neurons are inhibited

Question 18

theories for why we dream

Answer 18

exercises synapses when there is no external activity
memory consolidation
circuit testing - make sure it all works
– it is difficult to test these theories –

Question 19

circadian rhythm

Answer 19

24 hour sleep-wake cycle
endogenous cycle - without environmental cues
exogenous zeitgebers modulate this - external timing cues to sync the cycle to (light)

Question 20

brain areas and systems for circadian rhythms (2)

Answer 20

internal clock = suprachiasmatic nucleus of anterior hypothalamus
retinohypothalamic tract = links hypothalamus to eyes for syncing cycle to environment using light as a cue
–> intrinsically photosensitive ganglion cells have input to suprachiasmatic nucleus

lesion to suprachiasmatic tract dampens circadian rhythms of sleep