EEG, Sleep and Circadian Rhythms

Question 1

What does activity of the suprachiasmatic nuclei control?

Answer 1

Release of melatonin from the pineal gland

Question 2

What are inhibitory neurons in the suprachiasmatic nucleii stimulated by?

Answer 2

Light

Inhibit pineal gland

Question 3

What is orexin?

Answer 3

Excitatory neurotransmitter released from hypothalamus

Question 4

What is orexin required for?

Answer 4

Wakefulness

Question 5

What does defective orexin cause?

Answer 5

Narcolepsy

Question 6

How is level of consciousness assessed in an awake person?

Answer 6

Looking at behaviour, alertness, speech patterns and contents, reading, writing and calculating skills
Recording EEG

Question 7

What is the amplitude of an EEG wave?

Answer 7

Size of the wave

Ranges from 0-200uV

Question 8

What is the frequency of an EEG wave?

Answer 8

Number of waves per second

Ranges from 1-50+

Question 9

What is the effect of EEG wave frequency with neural excitation?

Answer 9

Frequency of waves increase

Question 10

What is the effect of amplitude of an EEG wave with neural excitation?

Answer 10

Amplitude decreases with increasing neuronal excitation

Question 11

What are the 4 main types of wave pattern seen in an EEG?

Answer 11

1. Alpha
2. Beta
3. Theta
4. Delta

Question 12

What type of wave pattern is seen in the relaxed, awake state in an EEG?

Answer 12

Alpha waves

Question 13

What type of wave pattern is seen in the alert, awake state in an EEG?

Answer 13

Beta waves

Question 14

What characterises alpha waves in an EEG?

Answer 14

High frequency

High amplitude

Question 15

What characterises beta waves in an EEG?

Answer 15

Higher frequency than alpha
Low amplitude
Asynchronous waves

Question 16

What characterises theta waves in an EEG?

Answer 16

Low frequency

Varied amplitude

Question 17

When are theta waves in an EEG common?

Answer 17

In children
Emotional stress and frustration in adults
During sleep

Question 18

What characterises delta waves in an EEG?

Answer 18

Very low frequency

High amplitude

Question 19

When do delta waves in an EEG typically occur?

Answer 19

In deep sleep

Question 20

What is stage 1 of a sleep cycle?

Answer 20

Slow wave
Non-REM
S-sleep
Slow eye movement
Light sleep - easily roused
High amplitude, low frequency theta waves

Question 21

What is stage 2 of a sleep cycle?

Answer 21

No eye movements
Frequency slows
Bursts of rapid waves (‘sleep spindles’)

Question 22

What is stage 3 of a sleep cycle?

Answer 22

High amplitude, very slow delta waves
Short episodes of faster waves
Spindle activity declines

Question 23

What is stage 4 of a sleep cycle?

Answer 23

Only delta waves

Deep sleep

Question 24

When is sleep walking/talking most likely to occur?

Answer 24

During stages 3 and 4 of sleep cycle

Question 25

What is stage 5 of a sleep cycle?

Answer 25

REM sleep When dreams occur 25% of sleep

Question 26

When does REM sleep occur?

Answer 26

Lasts 5-30 minutes every 90 minutes during a normal nights sleep Becomes more frequent throughout the night

Question 27

When are dreams most likely to occur?

Answer 27

REM sleep

Question 28

What prevents people acting out their dreams during REM sleep?

Answer 28

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

Question 29

What muscles show bursts of rapid activity during REM sleep?

Answer 29

Eye muscles

Question 30

What is REM sleep dependent on?

Answer 30

Cholinergic pathways in the reticular formation and projections to the thalamus, hypothalamus and cortex

Question 31

How do anticholinesterases affect REM sleep?

Answer 31

Increase time spent in REM sleep

Question 32

What happens to heart rate and respiratory rate in REM sleep?

Answer 32

Become irregular

Question 33

What happens to brain metabolism in REM sleep?

Answer 33

Increases

Question 34

What are the signs of sleep deprivation?

Answer 34

``` Impairment of cognitive function Impairment of physical performance Sluggishness Irritability Psychosis may also occur ```

Question 35

What functions does sleep support?

Answer 35

``` Neuronal plasticity Learning/memory Cognition Clearance of waste products from CNS Conservation of body energy Immune function ```

Question 36

What is insomnia?

Answer 36

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

Question 37

When does temporary, secondary insomnia occur?

Answer 37

In response to pain, bereavement or other crisis | Usually short lived

Question 38

What is the effect of barbiturates on sleep?

Answer 38

Depress REM and delta sleep Chronic use = increases time to fall asleep, decreases time spent in REM and stage 3 + 4 sleep Increases number of times awake during night

Question 39

What is the main issue with benzodiazepines?

Answer 39

Addictive which can cause problems on withdrawal

Question 40

What are the risks of taking hypnotic sleeping drugs?

Answer 40

Increased risk of RTA and fall fractures | Risk of dementia is increased 3+ months use

Question 41

What is the preferred approach to dealing with insomnia?

Answer 41

Behavioural changes to support induction of sleep

Question 42

When are night terrors most likely to occur?

Answer 42

In deep delta sleep Common in 3-8 year olds Occur early in the night

Question 43

What happens during night terrors?

Answer 43

Children thrash and scream May sit/stand with eyes open Child does not remember episode on waking

Question 44

When does sleep-walking occur?

Answer 44

Exclusively in non-REM sleep Mainly in stage 4 More common in children and young adults

Question 45

What are the common actions of a somnambulist?

Answer 45

Walk with eyes open Avoids objects Completes complex tasks Obey instructions

Question 46

What is narcolepsy?

Answer 46

Person enters directly into REM sleep with no warning