NMH 18: part 1

Question 1

Define sleep

Answer 1

Stereotypic or species-specific posture Minimal movement Reduced responsiveness to external stimuli Reversible with stimulation – unlike coma, anaesthesia or death

Question 2

What tells you about sleep

Answer 2

EEG, EOG and EMG (muscle tone)

Question 3

How does EEG, EOG and EMG change in stage 1&2 NREM, stage 3&4 NREM and stage 5 (REM)

Answer 3

EEG slows in stage 1&2 but increases a lot in 3&4, and is slow in REM EOG is much slower in NREM 1&2, but like awake in 3&4 and very high peaks in stage 5 (rapid eye movement so EOG is going to be high!) EMG reduces 1-4 and is almost nothing in REM… stops you acting out your dream

Question 4

T/F REM is only time you dream

Answer 4

F… also during other stages but maybe less

Question 5

How long is the sleep cycle and what is it made up of

Answer 5

Takes 90 minutes, goes through stage 1-5…. earlier on in sleep, NREM stages take up more time in the cycle

Question 6

What is like EEG like in REM sleep

Answer 6

More like awake compared to stage 3/4

Question 7

As well as EEG/muscular change, what other phsyioligcalt changes occur in sleep

Answer 7

Heart rate and respiratory changes— both reduce from stage 1-4, but increase into REM sleep and fluctuate a lot in REM

Question 8

What controls sleep

Answer 8

Reticular activating system (brainstem systems which project fibres onto cortex, hypothalamus and thalamus)

Question 9

t/f RAS allows for consciousness

Answer 9

True… kind of…. it’s necessary for consciousness but alone is not sufficient…. it’s like a dial, but it gates the activity of the cortex

Question 10

Which brain areas promote wakefullness and sleep

Answer 10

wakefulness: lateral hypothalamus (orexin) sleep: ventrolateral preoptic nucleus (in anterior hypothalamus)

Question 11

Interaction of hypothalamus with the RAS

Answer 11

Orexin based lateral hypothalamus activates the recticular activating system but the ventrolateral preoptic nucleus inhibits it (GABA)

Question 12

How does the suprachiasmatic nucleus impact on sleep

Answer 12

CIRCADIAN SYNCHRONISATION of sleep/wake cycle.

It synchronises sleep with falling light level, • It receives an input from the retina(becoming more acitive as light levels fall …

It interacts with the hypothalamus, (both the lateral nucleus, and the ventrolateral preoptic nucleus, changes therir activity according to induce sleep as light levels fall) and the RAS and with the pineal gland to release melatonin(changes various physioloical rprocesses in yo r body to fit with sleep)….

Question 13

Effects of sleep deprivation

Answer 13

Psychiatric and neurological together- Sleepiness, irritability, stress, mood fluctuations, depression, impulsivity, hallucinations Neurological- Impaired attention, memory, executive function Risk of errors and accidents Neurodegeneration (?) Somatic-Glucose intolerance Reduced leptin/increased appetite Impaired immunity Increased risk of cardiovascular disease and cancer Death

Question 14

t/f sleep loss affects brain activation on fMRI

Answer 14

T

Question 15

How can is sleep regulated (i.e. what can change if you have sleep loss)

Answer 15

Reduced latency to sleep onset Increase slow wave (NREM) sleep as a proportion of sleep if you missed this Or increase REM sleep after selective REM sleep deprivation

Question 16

Function of sleep

Answer 16

Restoration and recovery – but active individuals do not sleep more Energy conservation – 10% drop in BMR – but lying still is just as effective Predator avoidance – but why is sleep so complex? Specific brain functions – memory consolidation, …

Question 17

When do dreams most often occur

Answer 17

REM sleep (but can be both), and more easily recalled then

Question 18

What area of brain active in dreaming

Answer 18

Limbic system>frontal lobe More about emotion than reality

Question 19

Function of dreaming

Answer 19

Safety valve for antisocial emotions Disposal of unwanted memories Memory consolidation

Question 20

Outline insomnia causes

Answer 20

Most transient cases physiological: sleep apnea, chronic pain brain dysfunction: depression, fatal familial insomnia (caused by pryon protein like CJD) or night working

Question 21

Outline treatment of inoomnia

Answer 21

sleep hygiene, hypnotics (most enhance GABAergic circuits e.g. tamazepam or zopiclone) and sleep CBT

Question 22

What is narcolepsy

Answer 22

Falling asleep repeatedly during the day and disturbed sleep during the night

Question 23

What is hypersomnia

Answer 23

Too sleepy in the day… due to arousal in the night disrupting sleep wake cycle: -sleep apnea -anxiety

Question 24

Differentiate the type of disease of narcolepsy compared to insmnia

Answer 24

narcolepsy is a disease of the actual sleep/wake pathways (primary), whereas insomnia the pathway is probably fine and it’s other factors affecting this pathway

Question 25

What is cataplexy and when does it occur

Answer 25

In narcolepsy sudden, brief loss of voluntary muscle tone, often triggered by strong emotions e.g. laughter

Question 26

T/F in narcolepsy because of the disturbed sleep, REM and NREM sleep are comensated depending on which you have less of

Answer 26

F: there is Dysfunction of control of REM sleep

Question 27

Narolepsy is caused by what

Answer 27

Deficiency of orexin (=hypocretin)

Question 28

What can shift work lead to

Answer 28

physiological processes to become desynchronised sleep disorders, fatigue and an increased risk for some conditions such as obesity, diabetes and cancer