Sleep disorders appear in Paper B as part of both general adult psychiatry and liaison psychiatry. Understanding the interface between psychiatric conditions and sleep disturbance is essential, as sleep complaints are common to almost every psychiatric disorder but also represent primary sleep disorders that require specific management. The ICSD-3 (International Classification of Sleep Disorders) is the specialist classification, though ICD-11 is the reference for the exam.
Insomnia Disorder
ICD-11 criteria: Insomnia disorder is characterised by difficulty initiating or maintaining sleep, or early morning waking, that occurs at least several times per week for at least 3 months and is associated with significant daytime distress or functional impairment (fatigue, mood disturbance, cognitive impairment, reduced performance). The sleep disturbance must occur despite adequate opportunity for sleep. Primary insomnia is distinguished from insomnia secondary to another mental disorder (e.g., depression, anxiety) or to a medical condition (e.g., pain, hyperthyroidism) — though in practice, insomnia frequently co-occurs with these conditions and both should be treated.
NICE treatment (CG34): First-line is non-pharmacological: CBT for insomnia (CBT-I) — stimulus control, sleep restriction, cognitive restructuring, relaxation, sleep hygiene education. Sleep hygiene alone (regular sleep schedule, avoid caffeine/alcohol before bed, cool dark quiet room, avoid screens) is recommended as a first step but is insufficient for moderate-severe insomnia. Medication should be considered only when CBT-I is not available or has been ineffective. Z-drugs (zopiclone, zolpidem, zaleplon) and benzodiazepines are effective short-term but should be prescribed at the lowest dose for the shortest possible time (maximum 2-4 weeks) due to tolerance, dependence, and withdrawal risks. Melatonin (prolonged-release) is licensed for primary insomnia in patients aged 55 and over. Melatonin is also used for sleep-onset insomnia in children with ADHD or autism (off-label). Antidepressants with sedative properties (mitrazapine, trazodone, amitriptyline) are sometimes used for insomnia associated with depression but are not licensed for primary insomnia.
Exam key point: CBT-I is the first-line treatment. Z-drugs are second-line, short-term only. Antihistamines (promethazine, diphenhydramine) have minimal evidence and significant daytime sedation.
Sleep-Related Breathing Disorders
Obstructive sleep apnoea (OSA): Collapse of the upper airway during sleep leading to repetitive apnoeas (cessation of breathing for >10 seconds) and hypopnoeas, with associated oxygen desaturations and arousals from sleep. Symptoms: loud snoring, witnessed apnoeas, gasping or choking at night, excessive daytime sleepiness, morning headaches, irritability, poor concentration, low libido. Risk factors: obesity (especially neck circumference >40cm), male sex, older age, smoking, alcohol before sleep, craniofacial abnormalities. The STOP-BANG questionnaire (Snoring, Tiredness, Observed apnoea, Pressure/BP, BMI>35, Age>50, Neck circumference>40, Gender=male) screens for OSA. Diagnosis is by overnight polysomnography (AHI — Apnoea-Hypopnoea Index). Treatment: CPAP (continuous positive airway pressure) is first-line. Alternative: mandibular advancement devices, weight loss, positional therapy. OSA is associated with hypertension, cardiovascular disease, stroke, type 2 diabetes, and depression.
Central sleep apnoea: Cessation of respiratory effort due to loss of brainstem drive (not airway obstruction). Associated with heart failure, opioid use, and stroke. Treatment: adaptive servo-ventilation (ASV) or treating the underlying cause.
Psychiatric relevance: OSA frequently presents with depressive symptoms, fatigue, and cognitive complaints that are misattributed to primary depression. Treatment of OSA with CPAP improves these symptoms. The exam may present a patient with treatment-resistant depression and risk factors for OSA — the correct answer is to screen for sleep apnoea.
Central Disorders of Hypersomnolence
Narcolepsy (Gélineau syndrome): Tetrad of symptoms: 1) Excessive daytime sleepiness (the most disabling symptom, with irresistible sleep attacks). 2) Cataplexy (sudden bilateral loss of muscle tone triggered by strong emotions, especially laughter or surprise — the patient may have head drooping, jaw sagging, or fall to the ground, while remaining fully conscious throughout). 3) Sleep paralysis (inability to move or speak on waking or falling asleep). 4) Hypnagogic/hypnopompic hallucinations (vivid dreamlike experiences, often frightening, occurring at sleep onset or waking). Narcolepsy type 1 has cataplexy; type 2 does not. Pathophysiology: loss of hypocretin (orexin) neurons in the lateral hypothalamus, likely autoimmune-mediated. Associated with HLA-DQB1*0602. Onset typically in adolescence or young adulthood. Diagnosis by polysomnography and Multiple Sleep Latency Test (MSLT) showing mean sleep latency of less than 8 minutes and 2 or more sleep-onset REM periods. Treatment: modafinil (first-line for daytime sleepiness, a wakefulness-promoting agent with low abuse potential), methylphenidate, dexamfetamine. Cataplexy: sodium oxybate (gamma-hydroxybutyrate) or antidepressants (venlafaxine, clomipramine) that suppress REM sleep.
Kleine-Levin syndrome: Recurrent episodes of hypersomnia (sleeping 16-20 hours/day) lasting days to weeks, accompanied by hyperphagia, hypersexuality, and behavioural changes. Classically in adolescent males. Normal functioning between episodes. Ursodeoxycholic acid and lithium have some evidence for prophylaxis.
Idiopathic hypersomnia: Excessive daytime sleepiness without cataplexy and with long (often unrefreshing) naps. Distinguish from narcolepsy by the absence of REM-specific phenomena and the length of naps.
Circadian Rhythm Sleep-Wake Disorders
Disruption of the endogenous circadian pacemaker in the suprachiasmatic nucleus of the hypothalamus. Types: delayed sleep-wake phase (night owls — most common, common in adolescents), advanced sleep-wake phase (early birds, more common in older adults), irregular sleep-wake rhythm (disorganised, no clear circadian pattern, common in dementia), non-24-hour (free-running, common in blind individuals), shift work disorder, and jet lag disorder. Treatment: timed melatonin, bright light therapy (morning light for delayed phase, evening light for advanced phase), and strict sleep scheduling.
Parasomnias
Non-REM parasomnias (disorders of arousal): Confusional arousals (awakening confused, disoriented), sleepwalking (ambulation during NREM sleep), and sleep terrors (screaming, autonomic arousal, no dream recall). These occur during NREM stage 3 (slow-wave sleep), usually in the first third of the night. The patient has no memory of the event and cannot be easily awakened. Common in children, typically resolves with age. Treatment: reassurance, sleep hygiene, safety measures. In severe cases: clonazepam or scheduled awakenings.
REM parasomnias: REM sleep behaviour disorder (RBD): loss of the normal muscle atonia during REM sleep, causing the patient to act out dreams (punching, kicking, shouting). Classically associated with synucleinopathies (Parkinson’s disease, DLB, multiple system atrophy). Can precede the onset of Parkinson’s disease by years or decades. Treatment: clonazepam (first-line) or melatonin. Nightmare disorder: recurrent, unpleasant, well-remembered dreams. Treatment: imagery rehearsal therapy (IRT), prazosin for PTSD-associated nightmares.
Sleep-related movement disorders: Restless legs syndrome (Willis-Ekbom disease): distressing urge to move the legs, worse at rest, partially relieved by movement, worse in the evening or at night. Associated with iron deficiency (check ferritin), renal failure, pregnancy, and dopaminergic medications. Treatment: dopamine agonists (pramipexole, ropinirole — first-line), gabapentin, clonazepam. Periodic limb movement disorder: repetitive, stereotyped limb movements (typically dorsiflexion of the toes and ankle) during sleep, often associated with restless legs, causing arousals and daytime sleepiness.
Bruxism
Clenching or grinding of teeth during sleep, associated with stress, anxiety, and certain substances (serotonergic antidepressants, caffeine, alcohol). Can cause tooth wear and jaw pain. Treatment: occlusal splints (mouth guards), stress reduction, avoiding triggers. Clonazepam or botulinum toxin in severe cases.
Sleep and Psychiatric Medication
The effect of psychiatric medications on sleep is tested: SSRIs suppress REM sleep (can worsen restless legs and cause teeth grinding), mitrazapine improves sleep continuity (H1 blockade), olanzapine and quetiapine are sedating (H1, 5-HT2C), bupropion is activating (can worsen insomnia), modafinil is wake-promoting, melatonin promotes sleep onset. Antipsychotics with significant H1 blockade (olanzapine, quetiapine, chlorpromazine) improve sleep continuity. Clozapine causes hypersalivation that can worsen sleep for the patient.
High-Yield Recall Patterns
- First-line insomnia treatment: CBT-I. Z-drugs second-line, short-term (max 2-4 weeks).
- Narcolepsy tetrad: EDS, cataplexy (emotional trigger, preserved consciousness), sleep paralysis, hypnagogic hallucinations
- Cataplexy triggered by: Strong emotions, especially laughter. Key distinguishing feature from seizure/psychogenic.
- First-line for EDS in narcolepsy: Modafinil (wakefulness-promoting, low abuse potential)
- First-line for cataplexy: Sodium oxybate, or antidepressants (venlafaxine, clomipramine) — REM suppressants
- OSA screening tool: STOP-BANG — snoring, tiredness, observed apnoea, pressure, BMI>35, age>50, neck>40cm, male
- OSA first-line treatment: CPAP. Weight loss and MAD are alternatives.
- Restless legs first-line: Pramipexole or ropinirole (dopamine agonists). Check ferritin first.
- REM sleep behaviour disorder: Acting out dreams, loss of muscle atonia. Associated with synucleinopathies (PD, DLB). Treat with clonazepam.
- Sleep terrors vs nightmares: Terrors = NREM stage 3 (first third of night), no recall, screaming. Nightmares = REM (last third), well-remembered.
- Kleine-Levin: Hypersomnia + hyperphagia + hypersexuality in adolescent males. Episodic.
- Melatonin licensed for: Patients aged 55+ with primary insomnia (prolonged-release). Also used off-label for circadian phase disorders.
- Prazosin for: PTSD-associated nightmares
PsychStar’s Paper B question bank covers sleep disorders with questions calibrated to real exam style. Start with 5 free questions at psychstar.io/try.