From Multiple Treatment Failures to Functional Improvement With Lower-Sodium Oxybate in Idiopathic Hypersomnia: A Case Report.

Idiopathic hypersomnia (IH) is a chronic central disorder of hypersomnolence characterized by excessive daytime sleepiness despite adequate or prolonged sleep, with potentially substantial effects on occupational functioning, cognition, and driving safety. Pharmacologic management may be challenging when treatment is limited by inadequate efficacy or adverse effects. We report a young woman with severe hypersomnolence and a diagnosis of IH supported by clinical history and objective sleep testing. Multiple sleep latency testing demonstrated a mean sleep latency of one minute and 22 seconds, with no sleep-onset rapid eye movement periods (SOREMPs). Her Epworth Sleepiness Scale (ESS) score was 18/24, and symptoms included prolonged sleep duration, extended daytime naps, occupational impairment, and drowsy driving. Modafinil initially produced substantial benefit but subsequently lost efficacy despite dose escalation. Sequential trials of armodafinil, solriamfetol, mixed amphetamine salts, and methylphenidate were limited by tachycardia, inadequate efficacy or poor tolerability, paranoia, and persistent late-day sleepiness, respectively. Lower-sodium oxybate was subsequently initiated at 3 g once nightly but was reduced to 2.25 g because of significant nausea. With slower, individualized titration to 5.5 g once nightly, the patient reported substantial improvement in daytime sleepiness and functioning. Her ESS score decreased from 18/24 to 4/24, scheduled methylphenidate and caffeine were no longer required, and daytime napping was markedly reduced. This case illustrates the challenges of longitudinal pharmacologic management of IH and highlights the importance of individualized treatment selection, tolerability-guided oxybate titration, and assessment of functional outcomes beyond standardized sleepiness scores.