How long does it take for Sodium Oxybate to work? What's your opinion of this?

According to the Narcolepsy Network, although it affects more than 200,000 people in the US, narcolepsy is estimated to be undiagnosed or untreated in 75% of people with the disorder. This lack of recognition leads to delays in effective treatment and decreased quality of life. The US Food and Drug Administration has approved a variety of drugs to treat narcolepsy-associated excessive daytime sleepiness (EDS), including modafinil (Provigil), armodafinil (Nuvigil), methylphenidate, and amphetamine. Sodium oxybate (Xyrem) has been approved to treat the EDS and cataplexy associated with narcolepsy.