Sodium Oxybate in Idiopathic Hypersomnia

Inclusion Criteria: * Diagnostic of idiopathic hypersomnia (ICSD-3 criteria) * Age between 18 and 60 years-old * BMI between 18 and 35 kg/m2 * MSLT: mean sleep latency (MSL) ≤8 minutes and \< 2 SOREMPs, AND/OR total sleep time \> 11h/24h on 24-hours long-term polysomnography * Polysomnography recording: sleep efficiency \> 85%, total sleep time ≥6 hours, AHI \<10/hour, micro-arousals index \<15/hour, PLM index associated with micro-arousals \<10/hour. * Absence of sleep deprivation, assessed by actigraphy or sleep logs * ESS score ≥14 points * Written informed consent * National health insurance cover Exclusion Criteria: * Current alcohol intake or treatment with modafinil, amphetamine, methylphenidate, mazindol, pitolisant, neuroleptics, sedative hypnotics, barbiturates, general anesthetics, myorelaxants, other CNS depressants, antidepressants\*, anxiolytic drugs, anticonvulsive therapy, topiramate, inhibitors of GHB dehydrogenase (i.e. valproate, ethosuximide, phenytoin), budipine, dopamine antagonist antiemetics (except domperidone), opioids, benzodiazepines, Z-drugs, MAO inhibitors, COMT inhibitors, or sedative antihistamines. If patient has received such therapy, a washout-period of at least 15 days, or equivalent to 5 half-lives of the drug, prior to the inclusion in the study is required before starting treatment in this study. \*30 days for antidepressants * Previous intake of sodium oxybate * Succinic semialdehyde dehydrogenase deficiency, porphyria * Other cen…