Sleep disorders related to medical conditions

Overview - When Sickness Steals Sleep

• A prominent and severe sleep disturbance (e.g., insomnia, hypersomnolence) directly caused by the physiological effects of a general medical condition.
• DSM-5 Criteria:
  • Evidence from history, physical exam, or labs confirms the link.
  • Not better explained by another mental or sleep disorder.
  • Does not occur exclusively during an episode of delirium.
• Specify Type: Insomnia, Hypersomnolence, Parasomnia, or Mixed type.

⭐ High-Yield: Endocrine and neurological disorders are common culprits. For instance, hyperthyroidism often leads to insomnia due to ↑metabolic rate, while conditions like Parkinson's disease frequently disrupt sleep architecture.

Medical Causes - The Usual Suspects

• Neurologic Disorders

  • Parkinson's Disease: Strong association with REM sleep behavior disorder (RBD).
  • Alzheimer's Disease: Presents with "sundowning," agitation, and sleep fragmentation.
  • Stroke: Can precipitate insomnia or sleep-disordered breathing.
  • Epilepsy: Nocturnal seizures disrupt sleep architecture.

• Respiratory Conditions

  • COPD/Asthma: Nocturnal hypoxemia and frequent awakenings from dyspnea or cough.
  • Obstructive Sleep Apnea: Linked to anatomical obstruction (e.g., obesity, tonsillar hypertrophy).

• Endocrine/Metabolic

  • Hyperthyroidism: Causes hyperarousal and insomnia.
  • Hypothyroidism: Associated with hypersomnolence and sleep apnea.
  • Diabetes: Sleep disturbed by nocturia, neuropathy, or nocturnal hypoglycemia.

• Other Key Causes

  • Pain/Musculoskeletal: Fibromyalgia & arthritis cause pain-related arousals.
  • GI: GERD leads to nocturnal awakenings from reflux.

⭐ Fatal Familial Insomnia is a rare, inherited prion disease causing intractable insomnia, autonomic dysfunction, and dementia, ultimately leading to death.

Iatrogenic Causes - Pills & Potions

• Distinguish from substance-induced sleep disorder; here, sleep issue is a side effect, not the goal of use.
• Insomnia-causing Medications:
  • Corticosteroids (prednisone)
  • β-blockers (propranolol)
  • SSRIs (fluoxetine) - often transient
  • Stimulants (methylphenidate)
  • Decongestants (pseudoephedrine)
• Hypersomnolence-causing Medications:
  • 1st-gen antihistamines (diphenhydramine)
  • Benzodiazepines, Antipsychotics
• Nightmare-causing Medications:
  • β-blockers
  • Dopamine agonists (L-DOPA)

⭐ Propranolol, a highly lipophilic beta-blocker, readily crosses the blood-brain barrier and is frequently implicated in causing vivid dreams and nightmares.

Workup & Management - Sleuthing for Sleep

• History & Physical: Correlate timeline of medical illness and sleep symptoms.
• Initial Steps:
  • Sleep Diary/Log: Patient-reported data over 2-4 weeks.
  • Actigraphy: Wrist-worn device providing objective sleep-wake cycle data.
• Gold Standard Dx:
  • Polysomnography (PSG): Crucial to rule out primary sleep disorders (e.g., OSA, RLS) or characterize parasomnias (e.g., RBD).

⭐ Polysomnography is essential to differentiate a sleep disorder secondary to a medical condition from a primary sleep disorder (e.g., OSA) merely exacerbated by the illness.

Primary Goal: Always treat the underlying medical condition first.

High-Yield Points - ⚡ Biggest Takeaways

• Always treat the underlying medical condition first as the primary management strategy.
• Obstructive Sleep Apnea (OSA) is strongly linked to hypertension, atrial fibrillation, and insulin resistance.
• Restless Legs Syndrome (RLS) is frequently caused by iron deficiency anemia and chronic kidney disease.
• REM Sleep Behavior Disorder (RBD) is a major prodromal symptom for α-synucleinopathies (e.g., Parkinson's).
• Hyperthyroidism causes insomnia; hypothyroidism causes hypersomnolence.
• Nocturnal panic attacks arise from REM sleep, unlike sleep terrors (NREM sleep).