5 - Sleep-wake disorders

How is sleep defined?

A behavioural state characterised by: specific posture, reduced motor activity, suspension of consciousness, ↓ metabolism, ↓ interaction/reciprocity with env

What are the functions of sleep?

• exact functions unknown, but thought to be memory/learning consolidation

• Existing understanding comes from studies examining sleep loss/pathologica sleep conditions

What are the three assessment methods of sleep?

• clinical interview - routine assessment, evaluation of nature/severity/hisotry of sleep problems

• Self report questionnaire & symptom checklist - simple, quick, convenient

• Sleep diary - eval of insomnia

What are the two ways to objectively measure sleep?

• polysomnography (PSD) - in lab, controlled setting under supervision of technician, multiple channels of data collected - gold standard

  • Multiple physiological variables measures - air flow at nose, best around chest to measure breathing, sensor on finger to measure oxygen

• Actigraphy - wrist-watch devises, measures wrist movement to assess sleep, can measure in natural setting

What are the three distinct states and stages of sleep?

• states: wake, NREM, REM

• Stage 1: between awake & falling asleep. Light sleep

• Stage 2: disengaged from surrounding, body temp ↓, breathing and heart rate same - 40-55% of the night

• Stage 3: slow wave sleep (deep sleep), deepest & restorative sleep, blood pressure ↓, 10-20% (declines with age)

• REM sleep:brain is active, dreams occur, eye moves, body becomes immobile (paralysis), 25%

How does the sleep architecture as one ages generally?

• child: less awakening, more and longer slow wake sleep ⇒ less waking, more REM sleep, most NREM sleep

• Elderly: more awakening at night, less slow wake sleep ⇒ more waking, very little REM sleep, little NREM sleep

What are the two processes that regulates sleep?

• homeostatic sleep process (“Process S”) - sleep drive/pressure to sleep, ↑ after each hour waking up

• Circadian process (“process C”) - biological clock

  • Internal biological clock: suprachiasmatic nucleus in hypothalamus (light signals from retina conveyed to nucleus via nerve fibers

  • External cues: 24 hr light/dark cycle

  • Regulation of circadian rhythm - secretion of melatonin by pineal gland (melatonin reaches receptors in hypothalamus, body thinks it is dark)

• When there is the greatest gap bw process s and c = greatest urge to sleep

What are the four categories of consequences of sleep deprivation?

• physical - fatigue, daytime sleepiness

• Psychological - irritability, low mood, anxiety (↓ emotional regulation), ↑ risk of developing mood disorder

• Cognitive - ↓ vigilance, impaired concentration decision making memory, impact on academic performance

• Behavioural: daydreaming, aggressive, hyper/hypoactive

Does sleep compensation (sleeping more in the weekend to make up for lost sleep in the weekdays) work?

• no

• Disturbs biological clock - e.g. difficulty falling asleep on Sunday

What are the two major types of sleep disorders?

• Dyssomnias - disorder of falling/staying asleep. difficulties with timing/quantity/quality of sleep

  • E.g. insomnia, narcolepsy, circadian rhythm sleep-wake disorder

• Parasomnias - disorders of arousal & abnormal physical activities during sleep. unwanted abnormal behaviours/movements/experiences during sleep

  • e.g. disorder of arousal, nightmare disorder, REM sleep behaviour disorder

Explain the DSM5 diagnostic criteria for insomnia disorder

• difficulty initiating & maintaining sleep

• Early morning awakening with inability to return to sleep

• Frequency: at least three nights per week

• Duration: for at least 3 months

• Occurs despite adequate opportunity for sleep

What are some adverse consequences of insomnia

• ↑ risk of depression, anxiety, other mental illnesses

  • Insomnia bidirectional related to depression, insomnia is residual symptom in MDD

• Hypertension

• ↑ susceptibility to cold & chronic pain

What is the old and new understanding of insomnia as a condition?

• old: insomnia as a symptom of underlying physical/mental disorders (e.g. assume treating depression removes insomnia)

• New: insomnia as alone/comorbid clinical condition

Explain the Three-Factor Model (cause of insomnia)

Combination of:

• predisposing factors - biological, psychological, social factors

• precipitating factors - medical, psychiatric illness, stressful life events

• perpetuating factors - time in bed (perpetuates sleep difficulties), napping, conditioning (conditioned arousal)

What does an assessment entail?

• sleep history - nature, frequency, duration, treatment history, other symptoms, sleep wake schedule, routine

  • E.g. assessed using sleep diary or insomnia severity index

• Medical & psychiatric history, physical examination

Is a polysonography necessary for insomnia?

No, but can help rule out other sleep disorders (e.g. sleep apnea 0 breathing difficulties eating to waking at night)

What are some treatments for insomnia?

• pharmacotherapy

  • Usually to treat comorbid medical/psychiatric illnesses

  • E.g. benzodiazepine, zopiclone, zolpidem, antihistamine, sedative antidepressants

• Non-pharmacological treatment (first line treatment)

  • Psychoeducation/sleep hygiene

  • Behavioural treatment

  • Cognitive therapy

What are the advantages and disadvantages of using pharmacotherapy?

Adv

• immediate relief of insomnia symptoms (but temporary)

• Preventing learned insomnia due to increased anxiety at bedtime

Disadv

• tolerance, dependence, sedation

• Impairment of cognition, moot activity, performance

• Parasomnia

• Not long term

What is the CBT model of insomnia?

• dysfunctional cognitive, maladaptive beliefs, consequences, arousal

How effective is CBT for chronic insomnia?

• 70-80% achieve therapeutic response w CBT

• 40% achieve clinical remission

• CBT & benzodiazepine has comparable effectiveness during active treatment

  • But more sustainable, has long term, durable effects, better for sleep initiation problems

Explain what circadian rhythm sleep wake disorders is

• misalignment between sleep-wake pattern and what is desired/norm

• Diff types: delayed sleep phase (difficulty falling asleep), advanced sleep phase (sleeping/waking too early), irregular sleep-wake cycle, (jet lag + shift work)

What are the five treatment methods of CRSD?

• sleep hygiene

• Chronotherapy - progressive delay of sleep wake schedule until patient can consistently sleep earlier

• Bright light therapy - trick brain’s biological clock, early exposure to light = early wake time

• Melatonin

• Co-morbid psychopathology treatment

What is narcolepsy?

• disabling sleep order where people spontaneously sleep

• DSM: recurrent periods with irrepressible need to sleep, lapses into sleep or napping in the same day. At least 3x per week over 3 months

• 0.034% prevalence

What is the pathophysiology of narcolepsy?

Hypocretin deficiency

(Hypocretin = NT involved in maintaining stable wakefulness and suppressing REM sleep)

What are the symptoms of narcolepsy?

• sleep related hallucinations

• Sleep paralysis

• Cataplexy (temporary loss of muscle with preserved consciousness)

• Excessive daytime sleepiness

• Fragmented nocturnal sleep

What are some ways of managing excessive daytime sleepiness?

• sleep hygiene (scheduled naps, regular sleep wake schedule) - rarely effective alone, often paired with pharmacological treatment

• Pharmacological: methylphenidate, modafinik, sodium ox ate, selenite

What is parasomnia?

• abnormal behavioural/physiological events that accompany sleep

• During entry to sleep, within, or during arousals from sleep - not conscious

What are the two characteristic symptoms of NREM sleep arousal disorder?

• sleep walking - rising from bed during sleep and walking, during first third of sleep episode, person is unresponsive during, has amnesia for the episode, no impairment of mental activity/behaviour

• Sleep terrors - abrupt awakening from sleep, intense fear (e.g. tachycardia), relative unresponsiveness to efforts of comforting

What is the epidemiology of sleep walking? What are their aetiologies?

• childhood - more common, 5-30%, ↓ w age

  • Due to genetics & delayed CNS maturity

• Adults - less common, 2-5%, adult onset is rare (majority of adult sleepwalkers had childhood onset), associated with stress

  • Due to psychopathology, stress, medications, medical illnesses

What is REM Sleep behaviour disorder? (RBD)

• dream-enacting behaviours (movement during dreaming)

• Sleep related injuries

How is RBD linked to neurodegenerative disorders?

• RBD = precursor of neurodegenerative disorders

• 38-45% of RBD patients dev ^

• More than 80% of RBD patients develop Parkinson/dementia after 13 year follow up

How is RBD managed?

• screen for neurodegenerative disease

• Safety of sleeping env

• Pharmacological

  • Clonazepam (only manages symptomatic presentation, but underlying neurodegeneration)

  • Has complete/partial response

  • Side effects = confusion, fall, exacerbation

What is nightmare disorder according to DSM?

• repeated occurrence of extended, dysphoric, well-remembered dreams involving efforts to avoid threats - occurs during second half of major sleep episode

• When awake, rapidly oriented and alert

• Dream causes significant distress/impairment

Nightmares in children vs adults

• children: more common, ↓ w age, more prevalent in girls

• Adult: limited studies, varied prevalence due to diff operational def

Nightmares in context of psychopathology

• PTSD - highly prevalent & persistent (e.g. 5 nightmares/week for SA victims, up to 80-90% of concentration camp survivors), implicated in clinical course of PTSD

• MDD, panic disorder

• BPD

• schizophrenia

• alcohol dependence & abuse

• Comorbid w insomnia