Modified release gamma- hydroxybutyrate formulations having improved pharmacokinetics

A method of treating a human patient in need thereof, the method comprising:

• orally administering a formulation that comprises an immediate-release portion and a modified-release portion to the patient, wherein
• the orally administering occurs only once nightly,
• the formulation comprises an amount of gamma-hydroxybutyrate equivalent to 3.0 g, 4.5 g, 6.0 g, 7.5 g, 9.0 g, or 10.5 g of sodium oxybate,
• after the orally administering, the formulation releases gamma-hydroxybutyrate into the blood stream of the patient, and
• wherein the once-nightly formulation achieves a relative bioavailability (RBA) of greater than 80%.