Sleep wake disorders full details for md exam answer 10 marks

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I now have comprehensive material from Kaplan & Sadock's Synopsis of Psychiatry. Let me compile the full 10-mark MD exam answer.

Sleep-Wake Disorders - MD Examination Answer (10 Marks)

INTRODUCTION

Sleep-wake disorders are a group of conditions characterized by disturbances in the quantity, quality, timing, or architecture of sleep, resulting in significant distress or functional impairment. Sleep has three essential characteristics: (1) it is required for proper brain function - its failure impairs cognition and mood regulation; (2) it is not a single process - multiple distinct sleep types exist, each with unique functional importance; (3) it is not passive - high-degree brain activation and metabolism occur during sleep. Sleep disorders carry a direct cost of ~$16 billion annually in the US, with indirect costs exceeding $100 billion.

NORMAL SLEEP PHYSIOLOGY

Sleep is divided into NREM and REM stages. The table below summarizes electrophysiologic criteria:

Stage	EEG	EOG	EMG
Wakefulness	Low-voltage mixed frequency; alpha (8-13 cps) with eyes closed	Eye movements, blinks	High tonic activity
Stage 1 (NREM)	Low-voltage, theta (3-7 cps), vertex sharp waves	Slow eye movements	Slightly decreased tonic activity
Stage 2 (NREM)	Sleep spindles (12-14 cps), K-complexes	None	Low tonic activity
Stage 3 (NREM)	High-amplitude (>=75 microV) slow waves, 20-50% of epoch	None	Low tonic activity
Stage 4 (NREM)	High-amplitude slow waves >50% of epoch	None	Low tonic activity
REM sleep	Low-voltage mixed frequency; sawtooth waves	Rapid eye movements	Tonic atonia with phasic twitches

A normal sleep cycle lasts ~90 minutes, with 4-6 cycles per night. Deep NREM (stages 3 and 4 = slow-wave sleep) predominates early in the night; REM periods lengthen toward morning.

CLASSIFICATION (DSM-5 / ICSD-3)

DSM-5 classifies sleep-wake disorders into:

Insomnia Disorder
Hypersomnolence Disorder
Narcolepsy
Sleep-Related Breathing Disorders (Obstructive Sleep Apnea, Central Sleep Apnea, Sleep-Related Hypoventilation)
Circadian Rhythm Sleep-Wake Disorders
Parasomnias (NREM-related and REM-related)
Sleep-Related Movement Disorders

I. INSOMNIA DISORDER

Definition: Difficulty initiating sleep, maintaining sleep, or early morning awakening with inability to return to sleep - sufficient to impair daytime functioning.

Subtypes:

Psychophysiologic insomnia - conditioned arousal; patient "tries too hard" to sleep
Paradoxical insomnia - sleep-state misperception; patient overestimates wake time
Idiopathic insomnia - lifelong; begins in childhood
Insomnia due to mental disorder - most common type; 35% have a psychiatric diagnosis (MDD most frequent)
Inadequate sleep hygiene - behaviors not conducive to good sleep (caffeine, irregular schedules, daytime napping)
Behavioral insomnia of childhood - depends on specific stimulation for sleep initiation
Insomnia comorbid with medical condition - pain (synergy between pain and sleep loss), GERD, COPD, neurodegenerative disorders
Insomnia due to drug/substance - SSRIs, antiparkinsonian drugs, stimulants, rebound insomnia from alcohol/sedatives

Key point: Insomnia is an independent risk factor for suicide in MDD. In bipolar disorder, sleep deprivation can precipitate mania.

Treatment:

Pharmacologic: Benzodiazepines (short-term), non-benzodiazepine BzRA (zolpidem, zaleplon, eszopiclone), melatonin receptor agonist (ramelteon), orexin antagonist (suvorexant), low-dose doxepin. Eszopiclone, zolpidem-MR, and ramelteon are FDA-approved for long-term use.
Non-pharmacologic (first-line): Cognitive Behavioral Therapy for Insomnia (CBT-I) - includes stimulus control, sleep restriction, relaxation techniques (progressive muscle relaxation, abdominal breathing, guided imagery, biofeedback), sleep hygiene education, and cognitive therapy.
AASM recommends: suvorexant, eszopiclone, zaleplon, zolpidem, triazolam, temazepam, ramelteon, doxepin. Recommends against trazodone, diphenhydramine, melatonin, valerian.

II. HYPERSOMNOLENCE DISORDER

Definition: Excessive sleepiness (hypersomnia) not due to disrupted sleep or circadian dysfunction; likely results from fundamental neurologic sleep-regulation dysfunction.

Features: Daytime drowsiness, reduced attention, prolonged night sleep, difficulty waking. Serious, potentially life-threatening (driving accidents).

Treatment: CNS stimulants (modafinil, methylphenidate); good sleep hygiene; scheduled naps.

III. NARCOLEPSY

Core tetrad:

Excessive daytime sleepiness (EDS) - overwhelming, irresistible sleep attacks
Cataplexy - sudden loss of bilateral muscle tone with maintained consciousness, precipitated by strong emotions (especially laughter). Ranges from knee buckling to total paralysis lasting seconds to minutes.
Hypnagogic/hypnopompic hallucinations - vivid hallucinations at sleep onset or awakening
Sleep paralysis - transient inability to move at sleep onset or awakening

Types:

Type 1 (with cataplexy): Low or absent CSF hypocretin-1 (orexin); HLA-DQB1*06:02 strongly associated; likely autoimmune destruction of orexin neurons in hypothalamus
Type 2 (without cataplexy): Normal CSF hypocretin; less association with HLA

Diagnosis: Multiple Sleep Latency Test (MSLT) - mean sleep latency <8 minutes with >=2 sleep-onset REM periods (SOREMPs). Polysomnography done night before to rule out other causes.

Differential: Cataplexy confused with seizures or neurologic movement disorders. Disorders causing secondary cataplexy: hypothalamic tumors, sarcoidosis, multiple sclerosis, Niemann-Pick type C, paraneoplastic syndrome.

Treatment:

EDS: Sodium oxybate (most effective), modafinil/armodafinil (first-line), methylphenidate, amphetamines, pitolisant
Cataplexy: Sodium oxybate, venlafaxine, clomipramine, fluoxetine (REM-suppressants)
Sleep paralysis and hallucinations: Sodium oxybate, REM-suppressants

IV. SLEEP-RELATED BREATHING DISORDERS

A. Obstructive Sleep Apnea (OSA)

Repeated upper airway collapse during sleep causing apnea/hypopnea episodes >=10 seconds, oxygen desaturation, arousals.

Polysomnographic features: Cessation of oral/nasal airflow while abdominal/chest effort continues; oxygen desaturation; bradycardia, arrhythmias (PVCs); EEG arousal ("breakthrough"). Diagnosed by Apnea-Hypopnea Index (AHI): mild 5-15, moderate 15-30, severe >30 events/hour.

Treatment: Weight loss, CPAP (gold standard), dental appliance, surgery (uvulopalatopharyngoplasty). Comorbidities: hypertension, heart failure, stroke, diabetes, depression.

B. Central Sleep Apnea

Lack of respiratory effort (no chest/abdominal movement). Associated with heart failure, opioids, high altitude, brainstem lesions.

C. Sleep-Related Hypoventilation

Subtypes include Obesity Hypoventilation Syndrome, Congenital Central Alveolar Hypoventilation, Idiopathic Central Alveolar Hypoventilation.

V. CIRCADIAN RHYTHM SLEEP-WAKE DISORDERS

Pathophysiology: Misalignment between the endogenous circadian clock (suprachiasmatic nucleus, SCN) and the desired/conventional sleep-wake schedule. SCN fires with ~24-hour period; normally re-entrained by bright light, social cues, activity, stimulants.

Types (DSM-5):

Type	Feature
Delayed Sleep-Wake Phase	Sleep onset and wake times are delayed (night owls); common in adolescents
Advanced Sleep-Wake Phase	Sleep onset and wake times are earlier (familial form known); common in elderly
Irregular Sleep-Wake Rhythm	Disorganized, fragmented sleep pattern; associated with neurodegenerative disorders
Non-24-hour Sleep-Wake Rhythm	Progressive daily drift to later sleep onset; most common in blind individuals
Shift Work Disorder	Misalignment due to occupational schedule; associated with cardiovascular disease, GI disease, psychiatric disorders
Jet Lag Disorder	Transient; due to rapid time-zone crossing (ICSD includes; DSM-5 does not)

Treatment: Light therapy (properly timed), melatonin, chronotherapy (progressive delay of sleep time), modafinil (for shift work). Duration criteria: >=3 months (except jet lag).

VI. PARASOMNIAS

Undesirable physical events or experiences during entry into, during, or on arousal from sleep.

A. NREM-Related Parasomnias (arise from Slow-Wave Sleep)

1. Sleepwalking (Somnambulism)

Complex motor behavior during sleep with absent consciousness; patient may leave bed, walk around, perform activities
Occurs in first third of night from stages 3-4 NREM
Amnesia for episode; no purposeful action
Precipitated by: sleep deprivation, fever, CNS depressant withdrawal, stress
Treatment: Safety measures (lock doors/windows), low-dose benzodiazepines if frequent/dangerous

2. Sleep Terrors (Pavor Nocturnus)

Sudden arousal with intense fear, piercing scream, autonomic activation (tachycardia, diaphoresis)
Patient is unresponsive, confused; amnesia for episode
Unlike nightmares, few or no recalled dream images
Arise from slow-wave sleep; associated with psychiatric comorbidity in adults (trauma, PTSD)

3. Confusional Arousals

Milder form; partial awakening from NREM; patient is confused but returns to sleep; common in young children
These three (confusional arousals, sleepwalking, sleep terrors) lie on a continuum

4. Sleep-Related Eating Disorder

Classified as "sleepwalking with sleep-related eating" in DSM-5
Recurrent episodes of eating while partially asleep; may consume unusual foods; unaware; weight gain; hazardous food preparation

B. REM-Related Parasomnias (arise from REM Sleep)

1. Nightmare Disorder

Frightening, elaborate dreams from REM sleep; full recall on awakening (unlike sleep terrors)
Common in children ages 3-6; can persist after trauma (PTSD-related nightmares may be literal replays)
Medications causing nightmares: L-DOPA, beta-blockers; REM-rebound after REM-suppressant withdrawal

2. REM Sleep Behavior Disorder (RBD)

Loss of normal REM atonia; patient "acts out" vivid dreams; complex, often violent motor behavior
Strong association with neurodegenerative disorders (Parkinson disease, Lewy body dementia, MSA) - may precede neurodegeneration by decades
Treatment: Clonazepam, melatonin; safety precautions

3. Recurrent Isolated Sleep Paralysis

Transient inability to perform voluntary movements at sleep onset or awakening; full consciousness maintained; lasts seconds to minutes; may be accompanied by hypnagogic hallucinations

VII. SLEEP-RELATED MOVEMENT DISORDERS

1. Restless Legs Syndrome (RLS / Willis-Ekbom Disease)

Uncomfortable, irresistible urge to move the legs, worse at rest, in the evening/night, relieved by movement
Four essential criteria: urge to move, worsened at rest, worsened in evening, relieved by movement
Associated with iron deficiency (check serum ferritin), pregnancy, renal disease, peripheral neuropathy, folate deficiency
Treatment: Dopamine agonists (pramipexole, ropinirole) - first-line; iron supplementation if low ferritin; gabapentin/pregabalin; benzodiazepines

2. Periodic Limb Movement Disorder (PLMD)

Previously nocturnal myoclonus; brief stereotypic repetitive leg movements in NREM sleep
Extension of big toe; partial flexion of ankle, knee, hip; duration 0.5-5 sec; occur every 20-40 sec
Associated with aging, folate deficiency, renal disease, anemia, antidepressant use
Treatment: Dopamine agonists; benzodiazepines

3. Sleep-Related Bruxism

Grinding/clenching teeth during sleep; dental wear, jaw pain, headache; occurs during any sleep stage, most common in stage 2 and REM
Worsened by stress; occurs secondary to sleep-related breathing disorders, psychostimulants, SSRIs
Treatment: Occlusal splints (dental guards); relaxation; treat underlying OSA if present

4. Sleep-Related Leg Cramps

Painful calf muscle contractions during sleep; associated with metabolic disorders, electrolyte imbalances, diabetes, pregnancy

INVESTIGATIONS

Polysomnography (PSG) indications:

Diagnosis of sleep-related breathing disorders
PAP titration and treatment assessment
Sleep-related violent behaviors
Differentiating narcolepsy from other hypersomnolence disorders
Differentiating parasomnias from nocturnal seizures
Atypical parasomnias; neuromuscular disorders; PLMD

Multiple Sleep Latency Test (MSLT): Next-day after PSG; mean sleep latency <8 min; SOREMPs >=2 diagnostic of narcolepsy.

Actigraphy: Wrist-worn accelerometry; useful for circadian rhythm disorders; monitors sleep-wake patterns over 1-2 weeks.

SUMMARY TABLE: KEY COMPARISONS

Feature	Sleep Terrors	Nightmares	RBD
Sleep stage	NREM (stages 3-4)	REM	REM
Time of night	First third	Last third	Last third
Memory recall	None (amnesia)	Full recall	Variable
Motor activity	Partial (sits up, screams)	Minimal	Complex, violent
Autonomic arousal	Intense	Moderate	Present
Association	Trauma, stress	PTSD, L-DOPA, beta-blockers	Parkinsonism, Lewy body disease

CONCLUSION

Sleep-wake disorders represent a broad spectrum from primary disorders of sleep initiation/maintenance (insomnia), excessive sleepiness (narcolepsy, hypersomnia), abnormal behaviors during sleep (parasomnias), to movement disorders emerging from sleep. Their proper diagnosis requires understanding of sleep architecture, targeted history-taking (including bed partner's observations), and investigations such as polysomnography and MSLT. Treatment is disorder-specific, ranging from CBT-I and CPAP for insomnia and OSA respectively, to dopamine agonists for RLS and sodium oxybate for narcolepsy.

Source: Kaplan and Sadock's Synopsis of Psychiatry, 12th Edition (DSM-5 aligned); sleep stage classification from Rechtschaffen & Kales criteria.

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