If a sleep neroligist diagnoses idiopathic hypersomnia from sleep study, what would be the likely prognosis? is there anything to make it better?

Hypersomnia: There is criteria to classify different hypersomnia--- if narcolepsy and similar condition ruled out, you can be DX idiopathic hypersomnia, respond good to treatment , Ritalin (methylphenidate) better than provigil j clin sleep med. 2009 dec 15;5(6):562-8. Idiopathic hypersomnia: clinical features and response to treatment.

Good. Yes: Idiopathic hypersomnia is thought to be a neurological disorder characterized primarily by excessive daytime sleepiness. The most common treatments for excessive sleepiness are stimulant medications. However, these drugs are not a substitute for sleep. People with idiopathic hypersomnia often must allow more time in their schedules for sleep than most people, even while using such medications.