Sleep and Sleep Disorders

Question 1

What are the different features of sleep?

Answer 1

1. Species-specific sleep posture (lying/standing)
2. Behavioural quiescence (inactivity)
3. Rapid reversibility to wakefulness
4. Increased arousal threshold
5. Compensation following sleep loss.

Question 2

What are the different functions of sleep?

Answer 2

1. Energy conservation
2. Thermoregulation
3. Somatic and neural growth regulation
4. Immune regulation
5. Memory consolidation
6. Regulation of affect (effects mood)

Question 3

What is encephalitis lethargia? (sleep sickness)

Answer 3

Rare and severe brain disease causes inflammation -> presents with a range of neurological and psychiatric symptoms.
Thought to be due to damage to the brainstem.
Acute - excessive sleepiness, poor ocular motility, fever and movement disorders.
Chronic - parkinsonian-like signs.

Question 4

What anatomical area is responsible for sleep/wakefulness?

Answer 4

The ascending arousal system
Wake = upper brainstem and posterior hypothalamus - upper reticular formation projects to thalamus, hypothalamus and brainstem.
Sleep = preoptic area and adjacent hypothalamus

Question 5

What region of the brain controls the circadian rhythm?

Answer 5

The suprachiasmatic nucleus within the anterior hypothalamus
Activates by sunlight to cause wakefulness
In dark is not activated - allows sleepiness

Question 6

What is the role of the pineal gland in sleep regulation?

Answer 6

Secretes melatonin
‘The hormones of darkness’
Rises at night and suppressed by light
Help regulate the time of sleep

Question 7

What are the different stages of sleep?

Answer 7

Wake
NREM - divided into N1 (quick, some rolling eye movement, easily aroused), N2 (50% night) and N3 (20% night - memory consolidation)
REM (rapid eye movement) - occurs about 1.5hrs into sleep.

Question 8

What do the different stages of sleep look like on an EEG?

Answer 8

As go into different stages of sleep the complexes widen and the amplitude increases

N1 - theta waves
N2 - sleep spindles and K complex
N3 - delta waves
REM - Brandon fast sawtooth waves.

Question 9

What is the gold standard tool used to diagnose sleep disorders?

Answer 9

Polysomnography (PSG - sleep lab)
Records brain waves and vital signs, including HR, also looks at eye movement and leg movement.

Question 10

What is the significance of REM sleep related to sleep paralysis?

Answer 10

Completely paralysed body except from diaphragm and eyes
But with a fully awake brain

In sleep paralysis (pathological) abrupt wake before muscle tone resorted with dream-like hallucinations (REM paralysis is maintained for to long with a lag)

Question 11

What causes the muscle paralysis seen in REM sleep?

Answer 11

Muscle atonia
Descending inhibitory signal from the pons (PPRF) to the spinal motor neurons, leads to reduction in skeletal muscle tone
Except for the diaphragm and ocular muscles.

Question 12

What brain centres are responsible for keeping you awake?

Answer 12

LC (brainstem)
TMN (hypothalamus)
Raphe (brainstem)
The SCH increases the activity of orexin-releasing neurons which stimulates these wakefull centres
Which in turn inhibit the sleep centres.

Question 13

What regions of the brain are responsible for sleep?

Answer 13

VLPO (hypothalamus) promotes sleepiness
Is inhibited by SCN in the daylight
As night SCN inhibition is reduced and VLPO is stimulated by adenosine
VLPO causes inhibition of wake centres directly and indirectly by inhibiting Orexin-releasing neurons.

Question 14

What molecules prevent rapid switching/boomeraning between sleep and wake states?

Answer 14

Orexin

Question 15

What medications promote wakefulness?

Answer 15

Dopamine
Noradrenaline

Also histamine, orexin (same as hypocretin), Ach, glutamate

Question 16

What medication promotes NREM sleep?

Answer 16

GABA
Galanin

Question 17

What medication promotes REM sleep?

Answer 17

Acetylcholine
GABA
Glycine
Dopamine

Question 18

What does a hypnogram show of sleep?

Answer 18

The time spent in each stage of sleep (awake, REM, N1, N2, N3) shows when moves between these stages (like a timeline)

Question 19

Describe the normal contribution of each stages of sleep in a normal sleep cycle

Answer 19

Early in night - majority in N3 (deep sleep) with some transition to REM
Late night - more time spent in REM or N1/N2, increased amount of awakenings.
Awakenings are normal, often occur a lot more than we are aware of.

Question 20

What is meant by the circadian rhythm?

Answer 20

The timekeeper of sleep based on the presence of light
Based on 24hrs
Generated on SCN - receives eye input from retina to identify light intensity (retinohypothalamic tract)
Can be affected by blue light on phones (mimics sunlight)

Question 21

What are the two different regulatory systems of sleep?

Answer 21

Circadian rhythm - biological clock, responds to light cues (SCN)
Homeostatic drive - the need to sleep (example includes adenosine)

Question 22

How do our patterns of sleep change as we age?

Answer 22

At each stage of life there is a wide variation in the number of hours of sleep required by the individual.
Tends to decrease as we age
Newborn - 14-17hrs
Teenager - 8-10hrs
Older adult - 7-8hrs

Question 23

What is social jet lag in sleep?

Answer 23

Social jet lag - variation in bodies normal sleep pattern and forced sleep pattern from work/training routine etc.
Variation in sleep time between work and free days.
Mainly from chronic sleep deprivation and social jet lag.
Is sleeping more than 2hrs longer in bed during the weekend compared to the week.

Question 24

How does slow-wave sleep change as you age?
What are the consequences of this?

Answer 24

Decreases, particularly rapidly in 20s/30s into elderly.
This can decrease memory consolidation

Question 25

What are the general changes in sleep patterns as you age?

Answer 25

Homeostatic regulation of sleep declines with age - more reliant on circadian rhythm. Decreased slow-wave sleep Increased wakening Decrease in total sleep time Shift in circadian rhythm - tend to go to sleep earlier and wake up earlier. Decrease in melatonin.

Question 26

What are some consequences of severe sleep deprivation?

Answer 26

Memory disturbance Concentration difficulties Paranoia Delusions Can cause psychosis in vulnerable individuals

Question 27

What is the role of sleep in memory?

Answer 27

Needed for normal attention Learning and memory For initial information encoding - need to be alert to input data Can test this for Psychomotor vigilance test. Relearn during sleep - hippocampus encodes information as repeated reactivation, strengthening and reorganising neocortex. Slow eave sleep - declarative memory

Question 28

What is the impact of caffeine on sleep?

Answer 28

Adenosine antagonist - stimulant Safe daily dose - 200-400mg Half life 3.5 to 7hrs - dose dependent on how long to get out of the system Single shot expresso is about 60-75mg. Can cause insomnia, wrestlers legs and tremor Greater effect in non-caffine consumers.

Question 29

What advice should be given to patients trying to cut back of caffeine?

Answer 29

Count the cups Reduce by a cup a day to avoid withdrawal headache Also useful to consider smoking habits - smoking reduces caffeine half life by 30-50%, often people stop smoking and start drinking more caffeine.

Question 30

How does alcohol affect sleep?

Answer 30

Increases sleepiness Causes snoring due to changes to muscle physiology, can lead to sleep aponea Fall to sleep faster However alcohol is metabolised faster, this cause a drop in doses in the middle of the night causing awakenings, nocturia and disrupted REM sleep.

Question 31

What are the different types of sleep disorders?

Answer 31

Hypersomnias - too much Hyposomnia - insomnia Restless leg, parasomnia, seziure- seizures, nightmares Circadian rhythm disorders - jet lag, shift work

Question 32

How common are primary sleep disorders?

Answer 32

Insomnia - up to 15% Obstructive sleep apnoea 10% men and 5% women Parasomnia 2% adults and 30% of children Restless leg syndrome 10% Circadian rhythm disorder - up to 4% teenage males, much higher in mental health diagnosis Narcolepsy - up to 0.1%

Question 33

What can be used to determine if a patient is 'too sleepy'?

Answer 33

The Epworth Sleepiness Scale Give rankings for likelihood to fall asleep whilst completing an activity such as talking, watching TV, driving.

Question 34

What is obstructive sleep apnoea?

Answer 34

Snoring with partial or complete collapse of the upper airway leading to reduce in airflow This triggers a micro arousal to restore airway patency, resulting in fragmented sleep. Long term cycles lead to SANS activation + ROS + systemic inflammation -> long term complications such as HTN, CVD, Metabolic disorders.

Question 35

How does obstructive sleep apnoea present?

Answer 35

Partner often complains of excessive snoring and periods of apnoea Consequence - day time somnolence, compensated respiratory acidosis, hypertension

Question 36

What is the recommended management for sleep apnoea?

Answer 36

Weight loss Continuous positive airwat pressure (CPAP) - if mod or severe Intra-oral devices if CPAP not tolerated or only mild conditions with no daytime sleepiness DVLA should be informed in excessive daytime sleepiness Limited evidence to support pharmacological agents.

Question 37

What is the screening tool for obstructive sleep apnoea?

Answer 37

STOP BANG 6/8 = 80% chance of abnormal resp study at home S - snore T - tired during the day O - observed apnea P - pressure = high B - BMI more than 35 A - Age over 50yrs N - Neck circumference G - Gender - male

Question 38

What is central apnoea?

Answer 38

Brainstem problem Does not stimulate breathing Often: Heart failure Broad overprescribing of high dose opiods

Question 39

What is narcolepsy?

Answer 39

Loss of orexin - autoimmune Causes cataplexy - laughter causes sleep Vivid dreams Profound daytime sleepiness Sleep paralysis Sleep fragmentation

Question 40

What is NREM Parasomnia?

Answer 40

Incomplete awakening from slow wave sleep, eyes will be open. Including: Night terros Hypnagogic Sleep walking Sleep eating Sleep sex Confusional Arousals Wax and wane

Question 41

What are some risk factors for sleep apnoea?

Answer 41

Obesity - mechanical load on resp system Age - increase due to changes in muscle/fat around neck Male - difference in fat, hormones and anatomical variations Menopause - post increase FH - inherited variation in airway Smoking Alcohol/sedatives Anatomy - andeotonsillar hypertrophy etc Medical conditions - hypothyroidism, acromegaly, POCS

Question 42

What are the risk factors for NREM parasomnia?

Answer 42

Young onset Very common in children Up to 3% of adults - generally starting before they turn 20yrs Can be triggered again in adults if sleep disrupted - insomnia, stress, shift work etc Family history

Question 43

What is REM Sleep Behaviour Disorder?

Answer 43

Insidious progressive disorder of dream enactment and dream recall. The paralysis normally seen in REM sleep is not preserved When combined with lucid dreams that normally occur can cause patients to move out/shout out Commonly dream fighting off attacker. Can be a risk to themselves or partner from injury. Occurs in up to 1% older males - less common in females

Question 44

What test is required for diagnosis with REM sleep Behaviour Disorder?

Answer 44

Video polysonography Night sleep study with EEG and video - captures loss of REM atonia whilst in REM stage

Question 45

What conditions is REM sleep behaviour disorder often associated with?

Answer 45

Neurodegenerative disorders Parkinsons disease Dementia with Lewy Bodies (72% patient develop at 12yrs post diagnosis)

Question 46

What are some examples of circadian rhythm disorder?

Answer 46

Shift work disorder Delayed sleep phase syndrome - very late night owls Irregular sleep wake pattern Advacned sleep phase syndrome Non-24hrs (free running) sleep-wake pattern Jet lag disorder.

Question 47

What is insomnia?

Answer 47

Difficulty falling asleep and difficult staying asleep with daytime impact At least 3 months >3 days a week.

Question 48

What are some risk factors for insomnia?

Answer 48

Female Age 3Ps model - predisposition (genetic), precipitant and then perpetuating (sleep early then agitated as not sleep)

Question 49

How do we treat insomnia?

Answer 49

CBT for insomnia - sleep log, sleep rescheduling and education around sleep. Online - Sleepful Advice - try to get up at the same time everyday, go to bed when sleepy, avoid bringing day life into bedroom. Daylight and out of breath activity.