EEG, Sleep and Circadian Rhythms

Question 1

How does EEG work?

Answer 1

Uses electrodes placed on the scalp to record activity of the underlying neurons

Question 2

EEG readings show

Answer 2

wave patterns that reflect the electrical activity of the brain which can be analysed by amplitude and frequency

Question 3

In general, the frequency of wave patterns on EEG increase with

Answer 3

neuronal excitation

Question 4

What four main types of wave pattern are seen on EEG?

Answer 4

Alpha
Beta
Theta
Delta

Question 5

The characteristic of the wave pattern varies with

Answer 5

different states of consciousness

Question 6

In the relaxed awake state, EEG is characterised by

Answer 6

high frequency, high amplitude alpha waves

Question 7

In the alert awake state, EEG is characterised by

Answer 7

higher frequency (than relaxed), low amplitude, asynchronous beta waves

Question 8

Theta waves are characterised by

Answer 8

low frequency waves which vary enormously in amplitude

Question 9

Theta waves occur in

Answer 9

children
times of emotional stress/frustration in adults
during sleep in both adults and children

Question 10

Delta waves are characterised by

Answer 10

low frequency

high amplitude

Question 11

Delta waves occur in

Answer 11

deep sleep

Question 12

How many sleep stages are there?

Answer 12

5

Question 13

Describe stage 1 of the sleep cycle and types of wave present

Answer 13

Slow wave, non-REM sleep
Slow eye movements
Light sleep (easily roused)
High amplitude low frequency theta waves

Question 14

Describe stage 2 of sleep and type of waves present

Answer 14

Eye movements stop
Frequency slows
EEG shows busts of rapid waves (sleep spindles)

Question 15

Describe stage 3 of sleep and type of waves present

Answer 15

High amplitude very slow delta waves interspersed with episodes of faster waves
Spindle activity declines

Question 16

Wave type present in stage 4 sleep

Answer 16

Exclusively delta waves

Question 17

It is most difficult to rouse someone from what stages of sleep?

Answer 17

Stages 3 and 4

Question 18

What is stage 5 known as?

Answer 18

REM sleep (paradoxical sleep)

Question 19

REM sleep is characterised by

Answer 19

fast waves, similar to those of the awake state

Question 20

Deep sleep is the most restful type of sleep and is associated with

Answer 20

decreased vascular tone and BP
decreased respiratory rate
decreased basal metabolic rate

Question 21

Pattern of REM sleep

Answer 21

Lasts 5-30 mins every 90 mins during a normal nights sleep, becoming more frequent as the night progresses

Question 22

What prevents the “acting out” of dreams?

Answer 22

Inhibition of other skeletal muscles due to inhibitory projections from pons to spinal cord

Question 23

REM sleep is dependent on

Answer 23

cholinergic pathways within the reticular formation and their projections to the thalamus, hypothalamus and cortex

Question 24

What is insomnia?

Answer 24

Chronic inability to obtain the necessary amount or quality of sleep to maintain adequate daytime behaviour

Question 25

What are the two types of insomnia?

Answer 25

Chronic primary - no identifiable psychological or physical cause
Temporary secondary - response to pain, bereavement or physical cause

Question 26

At what point in sleep do night terrors occur?

Answer 26

In deep delta sleep, typically early in the night

Question 27

What is somnambulism?

Answer 27

Sleep walking

Question 28

At what point in sleep does somnambulism occur?

Answer 28

Exclusively in non-REM sleep, mainly stage 4

Question 29

What happens in narcolepsy?

Answer 29

Patients enter directly into REM sleep with little warning

Question 30

Consequences of chronic use of hypnotic drugs e.g. barbiturates

Answer 30

Increased time taken to fall asleep
Decreased time spent in REM and stage 3 and 4 sleep
Increase number of times awake a night

Question 31

What are circadian rhythms?

Answer 31

Physical, mental and behavioural changes that follow a roughly 24-hour cycle
Respond primarily to light ad dark in the environment

Question 32

Function of suprachiasmatic nucleus

Answer 32

Contains neurons which have an inherent 24-hour cycle entrained by external cues

Question 33

If the suprachiasmatic nucleus is destroyed, the circadian rhythm of sleep is

Answer 33

lost

Question 34

What is orexin?

Answer 34

Neuropeptide that regulates wakefulness, appetite and arousal