EEG and Sleep Flashcards

Question

What happens once we enter stage 4 sleep during the sleep cycle?

Answer 1

Following initial S-wave sleep. there is a gradual awakening towards Stage 1, but not like the initial stage 1, instead REM sleep during which EEG waves are Desynchronised, high frequency, low amplitude, very like the awake state.

Answer 2

1. Profound inhibition of body muscles as if the motor system has been turned off 2. EXCEPT for eye muscles which show bursts of activity 3. Hardest state of all to rouse someone from, even though the EEG is like that of the awake state (paradoxical sleep). (you do get spontaneous awakening however) 4. Sympathetic dominance: increased HR and BP, increased cerebral blood flow and brain temperature 5. >90% of people report dreaming if awakened from REM sleep. 6. All mammals and birds have REM sleep (except dolphins and spiny ant eaters)

Answer 3

1. First REM period is short, 5-10 minutes. REM duration increases as night progresses. 2. S-sleep becomes shallower. All Stage 3 and 4 S-sleep (= Delta sleep) occurs in the first half of the night = restorative, repairing sleep, increased Growth Hormone (20 fold increase)

Answer 4

1. Total sleep time decreases rapidly through childhood and adolescence. 2. Percentage of REM sleep also declines: - 80% in 10 week premature infant - 50% at full term declining to a stable... - 25% in adulthood -May be absent in senescence, >80 years old

Answer 5

Does the time course of change in REM sleep parallel brain maturation and the formation of functional synapses? Obvious need in development, but why adults? Is REM sleep needed in other situations where synaptic plasticity is important e.g. memory?

Answer 6

Very | May affect up to 25% of the population

Answer 7

Insomnia | Affects around 33% of adults

Answer 8

Termprary Insomnia: -As the result of a bereavement or other crisis Chronic Insomnia: -"Chronic inability to abtain the necessary amount or quality of sleep to maintain adequate daytime behaviour" Important to distinguish between the two

Answer 9

127 self-confessed insomniacs studied in a sleep laboratory. Their mean sleep duration was 7 hours and their mean onset time to sleep was 15 mins compared with average 8 hours sleep and 10 minutes onset time. When they woke they denied they had slept and had to be shown footage and data to be convinced otherwise SO THEY DO SLEEP, DREAM AND SNORE

Answer 10

Association of negative feeling with their normal sleep environment (may result in better sleep experience in a laboratory). Perhaps they dream they are awake.

Answer 11

The underlying anxiety/ depression should be tackled not the percieved symptoms of insomnia. Sleeping pills should only be considered in temporary insomnia. No-one should be on these long term

Answer 12

Many hypnotic drugs especially barbiturates depress REM and Delta sleep. (Decrease waking up during night in short term (initially)) Drug withdrawal -> "rebound effect" where there is a marked and immediate increase in the quantity of REM sleep, as if to catch up.

Answer 13

Rebound effect where patients expereince massive increase in REM sleep as if to catch up This brings a large increase in experience of nightmares

Answer 14

Whenever deprived of REM sleep there is always this catch up when able to sleep again. This catch up isnt seen with Delta sleep (gradual increase back to normal) Therefore indicates that REM must have an important physiological function

Answer 15

Benzodiazepines have less effect on REM sleep but are addictive and cause many problems on withdrawal Sleeping pills should NOT be given chronically

Answer 16

Nightmares have a strong visual component and are seen during REM sleep when PGO (pontine-geniculo-occipital) spikes can be recorded The shut off of the motor system may be to prevent us from acting out our dreams

Answer 17

Ponto-geniculo-occipital waves or PGO waves are phasic field potentials. These waves can be recorded from the pons, the lateral geniculate nucleus (LGN), and the occipital cortex regions of the brain, where these waveforms originate. The waves begin as electrical pulses from the pons, then move to the lateral geniculate nucleus residing in the thalamus, and then finally end up in the primary visual cortex of the occipital lobe. The appearances of these waves are most prominent in the period right before rapid eye movement sleep (or REM sleep), and are theorized to be intricately involved with eye movement of both wake and sleep cycles in many different animals.

Answer 18

The motor shut off that occurs during REM doesn't occur and patients act out their dreams. This can cause serious accidents and murder

Answer 19

Night terrors are associated with intense feelings particularly of fear and are non-REM phenomena Common in post-traumatic stress syndrome

Answer 20

Sleep walking Occurs exclusively in non-REM sleep, mainly in Stage 4 sleep. In view of the decline in Stage 4 sleep with age, its not suprising that it mainly affects children (predominantly boys) Somnambulists walk with their eyes open and avoid objects but have no recall of the episode if awakened

Answer 21

(0.04-0.09% of population) Irresistable urge to sleep, attacks last 5-30 minutes, usually during day and at behaviourally inappropriate times. May be precipitated by feelings of strong emotion (e.g. during laughter or sex) Often enter durectly into REM sleep Usually cataleptic as well (i.e. abrupt loss of muscle tone, but remain conscious). Effectively symptoms could be interperated as intrusion of REM sleep characteristics onto the waking cycle VERY DANGEROUS BCEAUSE OF ACCIDENT RISK

Answer 22

Cause has recently been linked to a hypothalamic neurotransmitter, orexin (aka hypocretin), which stimulates wakefulness and shows cyclic levels in blood, with a decrease at night. Post-mortem brains of patinets with narcolepsy have been shown to have an approximate 90% loss of orexin producing neurones. So, possibility of treatment now available. (Orexin also stimulates appetite)