DEFINITION

• Hypersomnolence disorder is a central sleep-wake disorder characterized by recurrent, excessive daytime sleepiness and prolonged unrefreshing sleep despite adequate nocturnal sleep, often with prominent sleep inertia, occurring at least 3 times per week for at least 3 months, and not attributable to narcolepsy, another sleep disorder, substance use, or a medical condition.[1][2]
• Unlike narcolepsy, hypersomnolence disorder is not associated with cataplexy, hypocretin deficiency, or ≥ 2 sleep-onset REM periods during sleep testing, and is characterized by prolonged, unrefreshing sleep with prominent sleep inertia rather than brief, refreshing naps.