Obstructive Sleep Apnea and Restless Legs Syndrome
Obstructive sleep apnea (OSA) is caused by repeated collapse of the upper airway during sleep, producing apneas (complete airway obstruction, ≥10 seconds of no airflow) and hypopneas (partial obstruction), typically accompanied by snoring and terminated by arousal. The severity metric — the apnea-hypopnea index (AHI) — counts events per hour: mild OSA = 5-15/hour; moderate = 15-30/hour; severe = >30/hour. Severe OSA (which can involve hundreds of apneas per night) produces chronic sleep fragmentation, intermittent hypoxia (oxygen desaturation to 70-80%), and HPA axis activation — creating a chronic inflammatory, hypoxic state that drives cardiovascular disease. Untreated severe OSA is associated with 3x higher stroke risk, 4x higher all-cause mortality, and dramatically elevated dementia risk.
OSA risk factors include: obesity (the most modifiable — each 10% weight reduction reduces AHI by 26%); male sex (2x higher prevalence than women, though women’s risk increases dramatically post-menopause); age (prevalence increases with age); craniofacial anatomy (retrognathia, high-arched palate); nasal obstruction; alcohol and sedative use (relaxes pharyngeal muscles); and smoking. Diagnosis requires polysomnography (lab-based full sleep study) or home sleep apnea testing (simplified home monitoring device) — the home test is sufficient for diagnosis in patients with high pre-test probability.
CPAP (continuous positive airway pressure) — a device delivering pressurized air through a mask to maintain airway patency during sleep — is the gold-standard treatment for moderate-severe OSA, with near-complete elimination of apneas and hypopneas when used correctly. Benefits of adequate CPAP treatment (4+ hours nightly): reduced daytime sleepiness, reduced cardiovascular risk, improved cognitive function, reduced depression and anxiety, and improved quality of life. Adherence is the primary challenge — approximately 50-60% of prescribed CPAP patients are adequately adherent. Auto-adjusting CPAP (APAP) is preferred over fixed-pressure CPAP for most patients. Alternatives for mild-moderate OSA or CPAP-intolerant patients: mandibular advancement devices (MADs — custom oral appliances that advance the lower jaw, enlarging the pharyngeal airway); positional therapy for position-dependent OSA; surgical options for anatomic contributors.
Restless legs syndrome (RLS) is a neurological condition characterized by an irresistible urge to move the legs, associated with uncomfortable sensations (creeping, crawling, tingling, burning) that are worse at rest and in the evening and relieved by movement. It affects 7-10% of the general population and is a significant contributor to insomnia. The pathophysiology involves dopaminergic dysfunction and — crucially — iron deficiency: the brain’s dopamine system is iron-dependent, and RLS is associated with reduced central nervous system iron stores even when serum hemoglobin is normal. Iron supplementation (in those with ferritin below 75 mcg/L) is the first-line treatment recommendation in current guidelines and produces significant symptom improvement in many patients. Dopaminergic medications (pramipexole, ropinirole) are effective but require careful long-term management due to augmentation risk.