Efficacy and Tolerance of Solriamfetol in Patients Affected with Idiopathic Hypersomnia.

Main inclusion criteria: * Age between 18 and 60 years-old * BMI between 18 and 30 kg/m2 * Diagnostic of idiopathic hypersomnia (ICSD-3 criteria) made in the last 5 years, based on Polysomnography (PSG) and Multiple Sleep Latency Test (MSLT) results, showing either: a mean sleep latency (MSL) of ≤8 minutes and \< 2 SOREMPs and/or a 24-h long term polysomnography recording showing total sleep time \>11h/24 hours. * Apnea-hypopnea index (AHI) \<15/hour, Apnea index \<10/hour, micro-arousals index \<15/hour, Periodic limb movement (PLM) index associated with micro-arousals \<15/hour on the PSG and MSLT performed within the past 5 years. * Absence of sleep deprivation, assessed by actigraphy or sleep logs for the 7 days preceding study inclusion * ESS score ≥11 points * Written informed consent * National health insurance coverage * Understand, read and speaks French well * The participant agrees to follow the contraceptive requirements detailed in the protocol. Main non-inclusion criteria * Non-stabilized hypertension * To be at imminent risk of suicide or injury to self, others, or property, or the participant has attempted suicide within the past year before screening, or has positive answers on items number 4 or 5 on the Colombia-Suicide Severity Rating Scale (based on the 6 months before randomization). * Other psychiatric conditions in the past 6 months * Presence of other central nervous system diseases: neurodegenerative diseases, seizure disorders, or history of head trauma associated with loss of consciousness * Prior history of psychotic episodes * Psychostimulant treatment with modafinil, methylphenidate, mazindol, pitolisant, ongoing or within 15 days prior to visit 1 * Treatment for obstructive sleep apnea-hypopnea syndrome ongoing or within 15 days prior to visit 1 * Treatment with psychotropic drugs: neuroleptics (i.e. clozapine, olanzapine, aripiprazole, …), sedative hypnotics (benzodiazepines, zolpidem, zopiclone), central nervous system depressants (barbiturates, …), antidepressants (SSRI (e.g. fluoxetine, sertraline, paroxetine…), serotonin and norepinephrine reuptake inhibitors (SRNI : e.g. venlafaxine, duloxetine), Monoamine oxidase inhibitors), anxiolytic drugs, anticonvulsive therapy (i.e. topiramate, inhibitors of GHB dehydrogenase (i.e. valproate, ethosuximide, phenytoin), or drugs for pain (level 2 (e.g. codeine, tramadol), and level 3 (morphine and derivatives)), ongoing or within 30 days prior to visit 1. * Treatment with dopamine antagonist antiemetics except domperidone, Catechol-O-methyltransferase (COMT) inhibitors, or sedative antihistamines ongoing or within 30 days prior to visit 1 =\> Of note, for all the above treatments: 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. Of note, for antidepressants, a washout of at least 30 days should be required. * Previously treated with solriamfetol * History of chronic alcohol or drug abuse within the prior 12 months * Malignant neoplastic disease requiring therapy within 12 months prior to Visit 1 or clinically relevant * Heart failure, unstable hypertension or other cardiovascular disease compromising the patient's wellbeing or ability to participate in this study * Renal or hepatic impairment * No regular sleep at night: shift work or other continuous non-disease-related life conditions * Has received any other investigational drug within 30 days or 5 half-lives (whichever is longer) prior to screening or plans to use an investigational drug (other than the study intervention) during the study