Sleep & Sleep Disorders

• What is sleep characterised by?

  Species-specific sleep posture

  Behavioural quiescence

  Rapid reversibility to wakefulness

  Increased arousal threshold

  Compensation following sleep loss
• What are the functions of sleep?

  Energy conversation

  Thermoregulation

  Somatic & neural growth regulation

  Immune regulation

  Memory consolidation

  Regulation of affect
• Which anatomical area is control of 'wake'?

  Upper brainstem & posterior hypothalamus
• What anatomical area is in control of 'sleep'?

  Preoptic area

  Adjacent anterior hypothalamus

  VLPO
• What regulates the circadian rhythm?

  Suprachiasmatic nucleus (SCN) within anterior hypothalamus
• What is the role of the pineal gland?

  Secretes melatonin

  Melatonin rises at night & suppresses by light
• What are the 3 sleep stages?

  Wake

  Non rapid eye movement sleep (NREM - divided into N1, N2 & N3)

  Rapid eye movement (REM)
• What is sleep paralysis?

  Abrupt wake before muscle tone is restored, with dream like hallucinations
• What happens to muscles during REM sleep?

  Muscle atonia
• What causes muscle atonia during REM sleep?

  Descending inhibitory signal from pons to spinal motor neurons -> profound reduction of skeletal muscle tone (apart from ocular muscles & diaphragm)
• Circadian rhythm has a direct link to RGCs that detect light intensity (retinohypothalamic tract).
• What happens to sleep when you age?

  Homeostatic regulation of sleep declines

  Decreased slow wave sleep

  Increased wakenings

  Decrease in total sleep time

  Average sleep at 20 = 8.5 hours

  Average sleep > 60 = 6.5 hours
• What are ageing clocks?

  Change in sleep with age

  Decreased melatonin from children to adults phase advance -> average sleep onset is 30 mins earlier every decade from 30s

  Teenagers have a delay in sleep phase through final stages of puberty
• Slow wave activity increases with encoding & learning of new information (particularly declarative memory).
• How is caffeine a stimulant?

  Adenosine receptor antagonist -> acts as stimulant
• How can caffeine affect sleep?

  Insomnia

  Worsen restless legs

  Tremor
• What is the effect of alcohol on sleep?

  Decreases sleep latency but fragments REM sleep in 2nd half of the night

  Bad for nightmare disorder, snoring & sleep apnoea, nocturia, REM sleep behaviour disorder, restless legs
• What are the possible symptoms of a sleep disorder?

  Hypersomnia

  Insomnia

  (Restless legs)

  Parasomnia

  Seizure

  Circadian rhythm disorders
• What causes narcolepsy?

  Loss of orexin (hypocretin)

  Human narcolepsy is an autoimmune condition due to loss of hypocretinergic neurons in the hypothalamus
• What is NREM Parasomnia?

  Incomplete awakenings from slow wave sleep inc.

  • night terrors
  • hypnagogic hallucination
  • sleepwalking
  • sleep eating
  • sleep sex
  • confusional arousals
• What is REM sleep behaviour disorder?

  Insidious progressive disorder of dream enactment often with injury & dream recall

  Loss of normal REM atonia (muscle paralysis)

  Strong association with neurodegenerative disorders (Parkinson's disease & Dementia with Lewy Bodies)
• What is insomnia disorder?

  Difficulty falling asleep and/or difficulty staying asleep with daytime impact

  At least 3 months, > 3 days a week
• What are the RFs for insomnia disorder?

  Women > men

  Increases with age

  Genetic predisposition

  Trigger

  Perpetuating factors (becoming frustrated, going to bed too early etc.)
• What is the treatment of insomnia disorder?

  CBT for insomnia (sleep diaries, sleep rescheduling, education around sleep)

  Advice to give to pts

  • get up at the same time every day
  • bedroom only for sleep (and sex)
  • agitation out of the bedroom (do not lie there)
  • physical activity in daylight
• What is the control of sleep-wake?

  Mutually inhibitory circuit controlled within brainstem

  Orexin stabilises the circuit

  
• How long is a sleep cycle in adulthood?


  90-120 mins
• How long is a sleep cycle in children?


  50-60 mins
• About 20% of the night is deep sleep (N3) mostly in the first 3 hours of the night.
• What is the average sleep duration in teenagers?


  8-10 hours
• What is the average sleep for 18-25 years?


  7-9 hours (6 or 10 could also be normal for some)
• Sleep is needed for normal attention, lerning & memory.
• We relearn during sleep.

  Hippocampus encodes, during sleep repeated reactivation, strengthening & reorganising within neocortex
• What are some common primary sleep disorders?

  Insomnia disorder

  Obstructive sleep apnoea

  Parasomnia

  Restless legs syndrome

  Circadian rhythm disorder?

  Narcolepsy
• What is the assessment for hypersomnias?


  Epworth Sleepiness Scale

  Give 8 situations and asked chance of dozing from 0-3

  Results:

  3-7 = normal

  0-2 = insomnia

  > 10 = excess sleepiness
• What is obstructive sleep apnoea?


  Snoring with partial or complete collapse of the upper airway -> complete or partial reduction in airflow (apnoea or hypoapnoea)

  Cycyle repeats throughout sleep -> fragmented night sleep, daytime sleepiness, prolonged, unrefreshing sleep, sore throat
• What are the risk factors of obstructive sleep apnoea?


  Age

  Male

  Obesity

  Large tonsils & adenoids

  Sedative drugs (opioids, alcohol)
• What are the high risk populations for obstructive sleep apnoea?

  Treatment-resistant HTN

  Treatment-resistant AF

  High dose opioids

  Bariatric surgery
• What is central sleep apnoea?


  Direct impact on medullary control of ventilations

  Many high dose opioids have central sleep apnoea
• What are the symptoms of narcolepsy with cataplexy?


  Cataplexy (emotionally triggered loss of muscle tone)

  Hypnogenic hallucinations (imaginary images or sensations that seem real and occur as a person is falling asleep)

  Excessive daytime sleepiness

  Sleep paralysis

  Sleep fragmentation at night
• What does Non REM parasomnia include?


  Sleep walking

  Sleep terrors

  Confusional arousals