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Sleep Disorders — Comprehensive Clinical Reference

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CLASSIFICATION (ICSD-3 / DSM-5)

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1. INSOMNIA

Definition

Epidemiology

• Most common sleep disorder; affects 10–15% of adults chronically
• Women > Men; elderly most affected

Pathophysiology

Clinical Features / Investigations

• Polysomnography (PSG): NOT routinely indicated for chronic insomnia; reserved when comorbid sleep disorder (OSA, RBD) is suspected
• Actigraphy: Useful for sleep-wake pattern assessment over weeks
• Blood tests: TSH, FBC, ferritin (to rule out secondary causes — hypothyroidism, iron deficiency)
• Sleep diary: Mandatory baseline tool

Differential Diagnosis

• OSA (snoring, witnessed apneas, obesity)
• Restless legs syndrome (urge to move legs at rest)
• Circadian rhythm disorder (phase shift pattern)
• Mood disorder (depression — early morning awakening; anxiety — sleep-onset difficulty)
• Substance/medication-induced (caffeine, alcohol, SSRIs, steroids, beta-blockers)
• Pain disorders
• Hyperthyroidism

Treatment

1. Sleep restriction therapy — limit time in bed to actual sleep time
2. Stimulus control — bed only for sleep/sex; fixed wake time
3. Sleep hygiene education
4. Relaxation techniques — progressive muscle relaxation, mindfulness
5. Cognitive restructuring — addressing dysfunctional beliefs about sleep

• Benzodiazepines/Z-drugs: AVOID in OSA (respiratory depression), pregnancy, substance use disorder, elderly (fall/fracture risk, Beers Criteria)
• Ramelteon: AVOID with fluvoxamine (CYP1A2 inhibitor)
• Suvorexant: AVOID with strong CYP3A4 inhibitors; use caution in narcolepsy
• Doxepin: AVOID in urinary retention, glaucoma, cardiac arrhythmias
• All sedative-hypnotics: AVOID in severe hepatic impairment

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2. OBSTRUCTIVE SLEEP APNEA (OSA)

Definition

• Mild: 5–14 events/hour
• Moderate: 15–29 events/hour
• Severe: ≥30 events/hour

Risk Factors

Clinical Features

• Symptoms: Loud snoring, witnessed apneas, nocturnal choking/gasping, unrefreshing sleep, excessive daytime sleepiness (EDS), morning headaches, nocturia, cognitive impairment, mood changes
• Signs: Obesity, large neck, Mallampati III-IV, crowded oropharynx, nasal polyps, retrognathia, hypertension

Investigations

Differential Diagnosis

• Central sleep apnea (no respiratory effort during apnea)
• Obesity hypoventilation syndrome
• Narcolepsy (EDS without snoring/apneas)
• Upper airway resistance syndrome
• COPD/asthma nocturnal symptoms
• Hypothyroidism
• Acromegaly
• Cardiac failure (Cheyne-Stokes breathing)

Treatment

• Weight loss (10% weight loss → ~25% AHI reduction)
• Positional therapy (avoid supine position)
• Avoidance of alcohol, sedatives, smoking
• Treat nasal congestion (intranasal steroids, decongestants)

• CPAP: Continuous PAP; most effective; pressure 4–20 cmH2O
• APAP (Auto-PAP): Self-adjusting; preferred for most patients
• BiPAP (BPAP): For patients intolerant of high CPAP or with central component or OHS
• ASV (Adaptive Servo-Ventilation): Central sleep apnea/complex apnea — CONTRAINDICATED in EF <45% with CSA (SERVE-HF trial)
• CPAP troubleshooting: aerophagia → APAP/BiPAP; nasal congestion → humidifier, nasal steroids; air leak → mask refitting; claustrophobia → desensitization

• Mandibular advancement devices (MADs) — mild-moderate OSA; preferred over CPAP for mild OSA
• Tongue retaining devices

• Uvulopalatopharyngoplasty (UPPP)
• Maxillomandibular advancement (MMA) — most effective surgical option
• Hypoglossal nerve stimulation (Inspire® device) — for CPAP-intolerant, AHI 15–65, BMI <35, central apneas <25%
• Tracheostomy — severe, refractory cases

• Solriamfetol, modafinil — for residual EDS despite CPAP
• Combination of topical oxymetazoline and intranasal lubricant — nasal symptoms

• ASV in HFrEF with EF <45%
• Oral appliances: active temporomandibular joint disease, poor dental status
• UPPP: does NOT cure severe OSA reliably; not a substitute for CPAP

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3. NARCOLEPSY

Definition

• Type 1: Cataplexy + hypocretin/orexin deficiency (CSF orexin-1 <110 pg/mL)
• Type 2: No cataplexy, normal orexin levels

"Tetrad" of Narcolepsy

1. Excessive Daytime Sleepiness (EDS) — irresistible sleep attacks; brief refreshing naps
2. Cataplexy — abrupt bilateral muscle tone loss triggered by strong emotion (laughter, surprise, anger); consciousness preserved; pathognomonic for Type 1
3. Sleep paralysis — inability to move at sleep onset/offset; awareness preserved
4. Hypnagogic/hypnopompic hallucinations — vivid visual/auditory hallucinations at sleep onset (hypnagogic) or offset (hypnopompic)

Pathophysiology

Investigations

Differential Diagnosis

• Idiopathic hypersomnia (no SOREMPs, no cataplexy)
• OSA (EDS from fragmented sleep)
• Kleine-Levin syndrome (episodic, with hyperphagia)
• Depression/psychiatric hypersomnia
• Seizures (cataplexy can mimic atonic seizures)
• Medication-induced sleepiness

Treatment (Three-Pronged Approach)

• Sodium oxybate (GHB): 4.5–9 g in divided doses at night; improves sleep architecture, reduces cataplexy and EDS; also available as mixed salts formulation (lower sodium)
• Scheduled naps (10–20 min, 1–2×/day) are highly effective and often overlooked

• Sodium oxybate — most effective for cataplexy
• SSRIs (fluoxetine, sertraline) — reduce cataplexy, sleep paralysis, hallucinations
• SNRIs (venlafaxine) — rapid cataplexy suppression; often used as first-line
• TCAs (imipramine, clomipramine) — effective but side-effect burden

• Sodium oxybate: AVOID with alcohol or CNS depressants; AVOID in succinic semialdehyde dehydrogenase deficiency; REMS program required (abuse potential)
• Stimulants: AVOID in severe cardiovascular disease, uncontrolled hypertension, history of stimulant abuse, closed-angle glaucoma
• Modafinil: reduces efficacy of hormonal contraceptives (enzyme induction)

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4. RESTLESS LEGS SYNDROME (RLS) / Willis-Ekbom Disease

Diagnostic Criteria (4 Cardinal Features)

1. Urge to move the legs, usually with uncomfortable sensations
2. Symptoms worsen at rest
3. Symptoms relieved by movement
4. Symptoms worse in the evening/night

Secondary Causes

Investigations

• Serum ferritin, iron studies — ferritin <50 µg/L = supplementation threshold
• Renal function, BUN/creatinine — exclude uremia
• FBC — exclude anaemia
• Peripheral nerve studies — if neuropathy suspected
• PSG — if periodic limb movements disrupting sleep are suspected

Treatment

• Iron supplementation when ferritin <50 µg/L (oral ferrous sulfate 325 mg TDS; IV iron if poor oral absorption or renal failure)
• Avoid triggering medications
• Regular moderate exercise; leg massage; warm baths; cool application
• Avoid caffeine, alcohol, nicotine near bedtime

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5. PARASOMNIAS (Key Disorders)

REM Sleep Behavior Disorder (RBD)

• Features: Dream enactment behaviors (punching, kicking, shouting during REM sleep); loss of normal REM atonia; very high conversion risk to synucleinopathy (Parkinson's, DLB, MSA — >80% in 10 years)
• PSG: REM without atonia
• Treatment: Clonazepam 0.25–2 mg HS; melatonin 3–12 mg HS (preferred in elderly/dementia)
• Safety: Bed rails, remove sharp objects from bedroom

NREM Parasomnias (Sleepwalking / Sleep Terrors)

• Features: Arise from slow-wave sleep; amnesia for episode; family history common
• Treatment: Safety measures; stress reduction; if frequent — clonazepam or imipramine; self-resolving in children

Nightmare Disorder

• Treatment: Imagery Rehearsal Therapy (IRT — CBT technique); prazosin for PTSD-related nightmares

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6. ICU MANAGEMENT OF SLEEP DISTURBANCES

Why Sleep Matters in the ICU

• Impaired immune function (↓NK cells, ↓IL-2, ↓IL-7, ↓phagocytosis)
• Insulin resistance and glucose intolerance
• Catabolic state: ↑O2 consumption, ↑catecholamines
• ↑Inflammatory cytokines (TNF-α, IL-6)
• Delirium (independently associated with worse outcomes)
• Delayed ventilator weaning

ICU Sleep Promotion — Non-Pharmacological (First Priority)

Pharmacological ICU Sleep Aids

• Benzodiazepines as primary sleep agents (promote delirium, respiratory depression)
• Antihistamines (anticholinergic effects → delirium)
• High-dose opioids beyond analgesia

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7. OPD PRESCRIPTION GUIDE

Insomnia — Sample OPD Prescription

Rx:
1. Zolpidem CR 6.25 mg PO HS × 2 weeks
   OR Suvorexant 10 mg PO HS × 4 weeks (preferred in elderly/comorbidities)
   OR Ramelteon 8 mg PO 30 min before HS (if predominantly sleep-onset difficulty)

2. Sleep hygiene counseling:
   - Fixed wake time daily (including weekends)
   - No screens 1h before bed
   - Avoid caffeine after 2 PM
   - No naps >20 min
   - Bedroom dark, cool (18–20°C), quiet
   - Avoid alcohol (disrupts REM)

3. Follow-up: 2–4 weeks

OSA — Sample OPD Prescription

Rx:
1. CPAP/APAP therapy — titrate to AHI <5 events/h
   - Starting pressure: APAP 4–16 cmH2O (auto-titrating)
   - With humidifier to prevent nasal dryness
   - Adherence target: ≥4h/night on ≥70% of nights

2. Weight loss program referral (dietitian + exercise)

3. Nasal fluticasone spray 50 mcg each nostril BD if nasal congestion

4. Avoid alcohol within 4h of bedtime; avoid sleeping supine

5. Screen and manage: HTN, DM, AF (common comorbidities)

6. Follow-up: 1 month (CPAP data download — check compliance and residual AHI)

Narcolepsy — Sample OPD Prescription

Rx:
1. Modafinil 100 mg PO morning (titrate to 200–400 mg/day)
   OR Solriamfetol 75 mg PO morning (titrate to 150 mg)

2. For cataplexy:
   Venlafaxine 75 mg PO morning
   OR Sodium oxybate 4.5 g HS + 4.5 g 2.5–4h later (titrate up)

3. Scheduled naps: 10–20 min after lunch

4. Avoid driving until symptom control established — must inform DVLA/licensing authority

5. Follow-up: 4 weeks

RLS — Sample OPD Prescription

Rx:
1. Check ferritin — if <50 µg/L:
   Ferrous sulfate 325 mg PO TDS with Vitamin C (enhances absorption)

2. Pramipexole 0.125 mg PO 2–3h before usual symptom onset
   (titrate weekly to 0.25 mg → 0.5 mg as needed)
   OR Gabapentin enacarbil 600 mg PO with dinner (preferred if pain, anxiety, or augmentation risk)

3. Avoid: SSRIs, antihistamines, caffeine, alcohol, nicotine

4. Follow-up: 4 weeks — assess for augmentation (symptoms earlier in day = augmentation)

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8. NUTRITION & SUPPLEMENT GUIDE FOR SLEEP DISORDERS

Key Nutritional Interventions

Dietary Recommendations

• High tryptophan foods: Turkey, chicken, eggs, dairy, pumpkin seeds, bananas — increase serotonin/melatonin substrate
• Mediterranean diet — associated with better sleep quality in epidemiological studies
• Avoid before bed: Caffeine (half-life 5–7h — avoid after 2 PM), alcohol (disrupts REM, fragmented sleep in latter half of night), large meals, spicy foods
• Kiwi fruit (2 kiwis, 1h before bed): Small RCTs suggest ↑sleep duration and efficiency — high in antioxidants and serotonin
• Tart cherry juice: Natural melatonin and tryptophan source; small RCTs show improved total sleep time
• Weight management: Critical in OSA — every 10% weight loss reduces AHI by ~25%

ICU / Critically Ill Nutritional Considerations

• Maintain glycaemic control (hyperglycaemia worsens sleep)
• Adequate tryptophan and branched-chain amino acid (BCAA) intake in enteral feeds
• Vitamin D, zinc, magnesium monitoring — deficiencies worsen sleep disruption and immune function
• Avoid excess carbohydrate loading (worsens CO2 production in ventilated patients)

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KEY CONTRAINDICATIONS SUMMARY

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QUICK REFERENCE: DIAGNOSTIC INVESTIGATIONS BY DISORDER

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• CBT-I is first-line for insomnia — more durable than medications
• ASV is contraindicated in HFrEF + CSA (SERVE-HF trial — ↑mortality)
• Cataplexy is virtually pathognomonic for narcolepsy Type 1
• RBD carries >80% risk of synucleinopathy conversion within 10 years
• Ferritin <50 µg/L requires iron supplementation in RLS even without frank anaemia
• Benzodiazepines in ICU worsen delirium — prefer dexmedetomidine or suvorexant

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100 Common Medical Terms — Complete Clinical Reference

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SECTION A — GENERAL CLINICAL / DIAGNOSTIC TERMS (1–20)

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SECTION B — EXAMINATION TERMS (21–30)

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SECTION C — INVESTIGATION / LABORATORY TERMS (31–45)

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SECTION D — IMAGING TERMS (46–52)

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SECTION E — SURGICAL TERMS (53–65)

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SECTION F — OPD (OUTPATIENT) TERMS (66–72)

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SECTION G — ICU / CRITICAL CARE TERMS (76–88)

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SECTION H — DISEASE CLASSIFICATION TERMS (91–100)

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BONUS: KEY ABBREVIATION QUICK-REFERENCE

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• Medical students: Learn Section A–D (foundation) first
• Junior doctors: Focus on Sections E–G (clinical application)
• Nurses/Allied health: Sections F–H + Abbreviations are most relevant
• Exam revision: Sections A, C, G, H are highest-yield