EEG, Sleep and Sleep disorders

Question 1

What are the four main types of brain wave that can be seen on an EEG?

Answer 1

Alpha (8 - 13 Hz)
Beta (14 - 30 Hz)
Theta (4 - 7 Hz)
Delta (<3.5 Hz)

Question 2

Describe how frequency and amplitude of EEG waves change in relation to neuronal excitation

Answer 2

Frequency generally increases with neuronal excitation

Amplitude generally decreases with neuronal excitation

Question 3

How does REM sleep look on an EEG?

Answer 3

Looks like an awake state - beta waves (with some theta waves)

Question 4

What do beta waves on an EEG indicate? What do they look like?

Answer 4

Awake and alert state
High frequency, low amplitude
Asynchronous

Question 5

Why are beta waves asynchronous?

Answer 5

The brain is doing many things at once; opposing polarities cancel each other out

Question 6

What to alpha waves on an EEG indicate? What do they look like?

Answer 6

Awake but relaxed state
High frequency, high amplitude
Waves are generally synchronised

Question 7

What do theta waves look like on an EEC? What state do they indicate?

Answer 7

State: light sleep
Low frequency
Amplitude can vary widely

Question 8

What do delta waves on an EEG indicate? What do they look like?

Answer 8

State: deep sleep

Very low frequency but high amplitude

Question 9

Which part of the brain is thought to control circadian rhythms?

Answer 9

Suprachiasmatic nuclei in the hypothalamus

Question 10

How much of sleep is REM?

Answer 10

25%

Question 11

What are sleep spindles?

Answer 11

1-2 second bursts of rapid brain activity

Occur during stage 2 of sleep

Question 12

What are K complexes?

Answer 12

Very high amplitude waves that occur during stage 2 of sleep

Question 13

Which stages of sleep are referred to as slow wave sleep? What type of EEG waves primarily occur in these stages?

Answer 13

Stages 3 and 4
Delta waves; stage 3 is mainly slower, larger theta waves with delta waves interspersed, whereas stage 4 is almost exclusively delta waves

Question 14

Which neurotransmitter is involved in REM sleep?

Answer 14

Acetylcholine

Question 15

Describe the aetiology/pathophysiology of narcolepsy

Answer 15

Dysfunctional orexin release from the hypothalamus due to loss of orexin-secreting neurones

Question 16

Which stage of sleep to narcoleptic patients generally enter into?

Answer 16

They enter directly into REM sleep

Question 17

What is somnambulism? In which stage(s) of sleep does it occur?

Answer 17

Sleepwalking

Occurs only in non-REM sleep, mainly in stage 4 (slow wave sleep)

Question 18

Why does the prevalence of somnambulism decrease with age?

Answer 18

The amount of stage 4 sleep decreases with age; this is primarily when somnambulism occurs

Question 19

Which neurotransmitter is involved in narcolepsy?

Answer 19

Orexin

- defective orexin signalling caused by loss of orexin-secreting neurones in the hypothalamus

Question 20

What is cataplexy?

Answer 20

Similar to sleep paralysis but occurs during the day. Often triggered by strong emotions.

Question 21

Why does sleep apnoea cause daytime sleepiness?

Answer 21

Frequent waking due to apnoea means that the slow wave sleep stages are not reached

Question 22

Which neurotransmitter is required for wakefulness?

Answer 22

Orexin

these neurones stop firing during sleep

Question 23

Describe the pharmacological management options for insomnia

Answer 23

Can be used for up to two months while waiting for other management methods such as behavioural therapy to take effect.

• Melatonin-agonists
• Non-benzodiazepine sedatives
• Benzodiazepines (occasionally)

Question 24

How prevalent is sleep apnoea?

Answer 24

Affects 1 in 20 adults

Question 25

Describe the management of narcolepsy

Answer 25

Adopt a regular sleep routine
Avoid excess caffeine and alcohol
Drug treatment: dexamfetamine and modafinil