To distinguish the difference between narcolepsy and obstructive sleep apnea (OSA), it is important for clinicians to have a good understanding of these two sleep disorders.

OSA, the most common type of sleep apnea, is a chronic, potentially lethal condition that causes poor sleep quality and increases the risk for other conditions, including coronary artery disease, congestive heart failure, arrhythmias, refractory hypertension, type 2 diabetes, stroke, and polycystic ovarian disease. Approximately 14% of men and 5% of women have OSA, although this can vary depending on the population.

For example, it is estimated that 70% to 80% of patients being evaluated for bariatric surgery and 60% to 70% of those with a history of stroke or transient ischemic attack have OSA. Of all the comorbidities, the one most studied is hypertension. Up to 50% of patients with hypertension have OSA.

Narcolepsy is a rare condition — with a prevalence of 0.02% to 0.06% — that affects both sexes equally. Most patients with narcolepsy begin to exhibit symptoms near the age of puberty, with a peak age of onset between 15 and 25 years. If a patient is older than 30 years of age, clinicians should consider a diagnosis of OSA before narcolepsy.

Narcolepsy is divided into 2 subtypes: narcolepsy type 1 (hypocretin deficiency with cataplexy) and narcolepsy type 2 (hypocretin deficiency without cataplexy). Patients with narcolepsy have an 85% to 95% reduction in the amount of hypocretin neurons, which results in instability of wake and sleep states. The classic triad of symptoms of narcolepsy include EDS with or without cataplexy, sleep paralysis, and hypnagogic hallucinations.

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