somnul

Question 1

how much do we sleep

Answer 1

we spend 33% sleeping

Question 2

what is sleep

Answer 2

state of immobility
responsiveness to world decreases
reversible - we can be woken up

Question 3

what is sleep

Answer 3

a state in which there is a shift in consciousness
We exhibit changes in various physiological processes: including brain activity, consciousness

Question 4

what are the 2 distinct classes of sleep

Answer 4

NREM
REM - small amplitude, fast, high, frequency EEG waves, rapid eye movements

Question 5

what are the brain activities during relaxed, wakefulness sleep

Answer 5

alpha waves
of high frequency
waves present when one begins a state of relaxation

Question 6

what are the brain activities during stage N1

Answer 6

Lightest stage of sleep
If someone wakes you up you might have not even realised you were asleep
irRegular, low amplitude
Brain activity begins to decline and there is decrease in frequency

Question 7

what are the brain activities during stage N2

Answer 7

deeper than N1
sleep spindles and k-complexes
k-complexes are the largest event that are seen

Question 8

what are the brain activities during N3

Answer 8

deepest stages of sleep
characterised by low frequency, high amplitude waves
delta waves

Question 9

what are the brain activities during REM sleep

Answer 9

irregular
low amplitude
high frequency waves
these reflect brain activity when we are awake

loss of muscle tone
more likely to dream vivid dreams

Question 10

what happens when we fall asleep

Answer 10

go through stages N1, N2 and N3
after an hour person begins to cycle back through the stages from N3 to N2 and then REM

sequence repeats every 90 mins

N3 decreases as the night progresses
length of REM increases as the night goes on

Question 11

2 process model describe 2 drives for sleep

Answer 11

homestatic
circadian

Question 12

homeostatic

Answer 12

the longer we’ve been awake, the greater out drive for sleep

substances building up the longer we are awake

Question 13

sleep homeostatis

Answer 13

longer youve been awake, the greater our sleep drive

when we are sleep deprived:
- sleep duration increases
- sleep intentisty increases

more difficult to wake someone from deep sleep N3 - when slow waves are present

Question 14

what is process s

Answer 14

when we are awake certain substances accumulate in the cerebrospinal fluid which can induce sleep

Question 15

adenosine

Answer 15

regulates NREM sleep
adenosine is a by-product of energy metabolism

with increased metabolism, neural activity and wakefulness extracellular adenosine builds up in the brain

presence of adenosine slows rate at which neurones fire - sleepiness

caffeine is an adenosine blocker - increase in time spent awake

Question 16

what is circadian process

Answer 16

circadian rhythm - biological process that displays an endogenous, entrainable oscillation of about 24h

circadian - about a day
endogenous - something from within
entrainable - we can use environmental cues to adjust our rhythms to the world around us

Question 17

entrain our rhythm

Answer 17

we use zeitgeber - time giver
external cues that can control the timing of circadian rhythms

zeitgebers can be manipulated to increase of reduce length of circadian rhythms

light, excercise

Question 18

individual differences in circadian rhythms

Answer 18

circadian phase exhibits wide inter-individual variation

individual phase called chronotype

some ppl like functioning in the morning

-evening types have a phase delayed circadian rhythm
-morning types have a phase advanced circadian rhythm

chronotype influenced by genes

Question 19

what is the evolutionary advantage of different chronotypes

Answer 19

help early social individual humans be active and alert at different times of day to enhance survival

Question 20

why do we have a biological clock

Answer 20

allows animals to be active during the times that are most adaptive for them - humans in the day time

allows us to function on same schedule and function as a society

Question 21

what is evidence for biological clock

Answer 21

if someone lived without external cues to know what time of day it is

free running pattern
can still demonstrate regular sleep wake cycle

Question 22

suprachiasmatic nuceli

Answer 22

master clock
coordinates clocks throughout the body
clock genes are important in generating these cycles
genes interact producing an auto regulatory feedback loop

Question 23

SCN

Answer 23

tiny region in anterior hypothalamus
superior to the optic chiasm - where optic nerves cross

Answer 24

scn controls the pineal gland
- important for production of melatonin
melatonin is the darkness hormone - tells body what it should be doing when ti gets dark - falling asleep

in animals melatonin tells them to be active

when there is less light, the SCN tells brain to make more melatonin which can make you feel drowsy

melatonin is inhibited by light

Answer 25

melatonin has circadian rhythm increases as evening sets in peaks in middle of night then decreases lowest level just before we wake up

Answer 26

SCN synchronises local clocks in organs and tissues throughout the body, either through hormones or changes in body temperature there are some gene operated clocks that are independent of the brains master pacemaker - liver, lung, testis

Answer 27

specific lesions of SCN disrupt various circadian cycles including sleep-wake cycles this does not affect sleep length, but affects periods or cycles of sleep

Question 28

bilaterial lesions

Answer 28

bilateral lesions of SCN have abolished some circadian rhythsm but not others other brain regions could be involved SCN lesions block entrainment to light but not to other factors like food

Question 29

other areas involved in sleep

Answer 29

VLPO becomes more active when we fall asleep inhibits brain areas involved in arousal ARAS

Answer 30

objective measures subjective measures

Question 31

polysomnography

Answer 31

electrical brain potentials can be used to classify levels of arousal and stages of sleep includes EEG EOG AND EMG EEG - recording electrical activity from brain by placing electrodes on the scalp EOG - electrodes placed on outer canthus of the eyes. can record eye movement EMG - recording muscle activity. electrodes can be placed on the chin or legs - provides info about REM sleep

Question 32

PSG

Answer 32

stages of sleep sleep stages transitions microstructure (sleep spindles / K complexes) - found during N2

Answer 33

sleep onset latency - time it takes to fall asleep total sleep time sleep efficiency - time spent in bed that youre alseep wake after sleep onset number of awakenings abnormalities during sleep muscle activity: restless leg respiratory: apnoeas (pauses in breathing during sleep), hypopneas (reduction in breathing)

Question 34

drawbacks

Answer 34

expensive time consuming difficult to get data collected over long periods people dont want to spend extensive periods in sleep labs participants sleep worse during the first night sometimes opposite effect is observed - they sleep better in a sleep lab

Question 35

first night effect

Answer 35

1st and 2nd night spent in lab during 1st night, part of left hemisphere stayed alert during sleep left hemisphere fell into a lighter sleep compared to right left remained responsive to sounds in environment ensuring safety

Question 36

drawbacks

Answer 36

subjective sense of poor sleep children with depression report struggling to sleep at night but in sleep lab there is less strong evidence for this paradoxical insomnia - someone may report symptoms of insomnia but these are not verified by sleep lab

Question 37

actigraphy

Answer 37

wrist watch like device non invasive assesses movement during sleep doesnt tell us about sleep stages but tells us about sleep onset latency, total sleep time, time in bed, number of wakings

Answer 38

useful for assessing circadian rhythm, free running period, circadian rhythm disorders, excessive daytime sleepiness, and periodic limb movement

Question 39

pros

Answer 39

non disruptive used at home cons issues with accuracy cant distinguish between rest and sleep can overestimate sleep

Question 40

orthosomnia

Answer 40

ppl are becoming obsessed with perfect sleep preoccupation with maintaining perfect sleep there is no perfect sleep

Question 41

questionnaires

Answer 41

sleep quality index insomnia severity index preference in chronotype

Question 42

pros of self report

Answer 42

easy to administer can recruit large samples for insomnia self report is key

Question 43

cons of self report

Answer 43

reporter bias discrepency between subjective and objective data people may not be aware of sleep apnoea

Question 44

measuring circadian phase markers

Answer 44

body temperature melatonin measure this to tell us about circadian phase