Stay(2005)

A dedicated New York psychiatrist Sam Foster urgently attempts to stop a secretive and unusual young patient he inherited, Henry Lethem, from carrying out a planned suicide on the eve of his 21st birthday. But Sam's investigation of Henry has reality-shattering effects on the psychiatrist. As Sam is drawn deeper into the web of Henry's life--and then into the labyrinth of his subconscious--it puts stress on Sam's relationship with his artist girlfriend and former patient Lila. But soon Sam's own tightly-held grip on the rational world begins to melt away. Faced with increasingly surreal encounters and a Manhattan transformed into a wildly shifting dreamscape, Sam can no longer figure out what is true and what is happening only in his head, nor where he begins and Henry ends.