This study is focused on patients with major depressive disorder (MDD), a condition that leads to persistent feelings of sadness, and excessive daytime sleepiness (EDS), meaning they feel very sleepy during the day. The study tests a medicine called solriamfetol to see if it helps. It involves several stages: a screening period to see if you qualify, an open-label period where everyone gets solriamfetol, and a double-blind randomized withdrawal period where you might either continue with solriamfetol or receive a placebo (a pill with no active medicine) without knowing which you are getting. This helps scientists see if solriamfetol really works. You must be between 18 and 65 years old, meet the criteria for MDD, and be able to follow study procedures.

• The study involves multiple visits and lasts several weeks.
• Participants may receive a placebo, which looks like the real medicine but has no active ingredient.
• It's important to check if you have any other health conditions, as some may exclude you from participating.