Sleep physiology and disorders

Question 1

What are the two stages of sleep?

Answer 1

2 stages of sleep: rapid eye movement sleep and non-rapid eye movement sleep

Question 2

Describe REM sleep

• what proportion of sleep is this
• what is this assoc. with
• what is this particularly good for?

Answer 2

25% sleeping time

associated with dreaming 

skeletal muscles become atonic with exception of eyes and diaphragm 

good for brain development – infants have more REM sleep

Question 3

Describe NREM sleep

-how many phases?

Answer 3

subdivided into 4 phases – with progressively slower wave forms on EEG

this is more important as the cortex relaxes

Question 4

What are the 3 factors that influence sleep?

Answer 4

homeostatic reflex – the longer you’re awake, the easier it is fall asleep

emotional – if feel nervous can’t sleep 

circadian rhythm – body clock: changes with age

Question 5

What scale can be used to assess sleepiness?

Answer 5

epworth scale

Question 6

What are sleep disorders called?

Answer 6

parasomnias

Question 7

What is REM sleep behavior disorder?

• what happens?
• what is reported by partner?
• what is the treatment

Answer 7

acting out dreams

often seen in alpha-synucleinopathies (e.g. MSA) 

sleeping partner reports patient kicking and punching in sleep 

waking is associated with dream content 

treat with benzodiazepine

Question 8

What is NREM parasomnia?

Answer 8

these occur in the first half of sleep and include sleep walking and night terrors

Question 9

What is narcolepsy?

-what is the criteria?

Answer 9

This is both a disorder of the ability to sustain wakefulness voluntarily and a disorder of REM sleep.

Needs A and B to be present:

A irresistible urges to fall asleep for 15-30 min: patient awakes refreshed. Sleep at night is often disrupted (excessive daytime somnolence)

B cataplexy: loss of posture (head droops, eyelids droop or falling to the floor) provoked by an emotional response e.g. laughter
(sudden weakness or loss of muscle tone without loss of consciousness)

C sleep paralysis: awakes not able to move – this can be normal

D hallucinations just before dropping off to sleep or upon wakening

E fugue-like states with autonomic obedience – almost a waking prolonged absent-minded daydream state

B/C/D/E – intrusion of REM sleep into transition between wakefulness and sleep

Question 10

How is narcolepsy diagnosed?

• what is the most common cause?
• what is the treatment?

Answer 10

seems to be dysregulation of REM sleep

diagnosed clinically and with the multiple sleep latency test – abnormal if non-sleep deprived subject sleeps before 8mins (8-10 is borderline) and REM onset 

most common causes: sleep deprivation or chronic sleep apnoea 

treatment is modafinil/amphetamine for sleep disorder 

Tricyclic or SSRI for cataplexy

Question 11

What is the most common cause of excessive daytime somnolencE?

Answer 11

Sleep apnoea

Question 12

What are the clinical features of sleep apnoea?

Answer 12

Common cause of excessive daytime somnolence

Unrefreshed from waking from sleep 

Morning headaches 

Often snore 

Partial upper airways obstruction becomes further narrowed or obstructed during sleep

Question 13

How can sleep apnoea be diagnosed? what is the treatment?

Answer 13

Sleep recordings reveal arousals from sleep

5-20/h mild 

20-40/h moderate 

>40 severe 

trial of continuous positive airway pressure may be necessary 

some patients require surgery to remove excess soft tissue from the upper airways

Question 14

What is idiopathic hypersomnolence? what is the treatment?

Answer 14

under-recognised and may affect the young

urges to sleep occur and last for 1-2hrs and are unrefreshing 

treatment – modafinil