Happy Head by Josh Silver

A completed duology, grab Dead Happy to continue the series! 

A bold new dystopian thriller about an experimental mental health retreat center for young adults where everything is not what it seems--and one boy who will risk everything to escape.

Seb has been selected for a new experimental mental health center called HappyHead, designed to solve the national crisis of teenage unhappiness. There he and fellow participants will complete in a series of assessments meant to test them, so they can better face the challenges of the real world. Seb is determined to win so he can change how people see him and make his parents proud.

But then Seb meets a mysterious participant named Finn who has drawn unwanted attention to himself by resisting the program's rules. The leaders want everyone to believe Finn is mentally unstable but as Finn exposes cracks in the system around them, Seb is left questioning the true nature of the challenges--and wondering if Finn is actually the only one he can really trust.

Something sinister is at play...and as the assessments take a dark turn, it becomes impossible to ignore the voice in his head telling him that even if he wins, there might be no way out.