The FDA approved Jazz Pharmaceuticals’ Sunosi (solriamfetol) for improving alertness in patients suffering from narcolepsy or sleep apnea.

The approval followed positive results from a Phase III trial—four randomized, placebo-controlled studies of more than 900 adults. By week 12, patients in the Sunofi group showed improvement in their wakefulness scores at two separate monitoring times.

Some analysts think Jazz has a big winner on its hands and are forecasting peak annual sales of more than $500 million. The company plans to launch Sunosi in the U.S. within the next three months.