In the movie "Fight Club", the character played by Edward Norton suffers from which health issue?

In the 1999 film "Fight Club", based on the Chuck Palahniuk novel "Fight Club", was directed by David Fincher. In the movie, the Narrator is portrayed by Edward Norton and Tyler Durden is played by Brad Pitt. It was said that the actors began preparation for their roles by taking lessons in boxing, grappling, taekwondo, and soap making. Pitt made the decision to visit a dentist to have pieces of his front teeth chipped off so that the character of Tyler would have imperfect teeth. The pieces were restored after the film's production concluded.

Norton, the unnamed narrator, is very discontented with his white-collar job. He forms a "fight club" with soap salesman Tyler (Pitt), Norton's other chaotic and charismatic personality at night during periods of insomnia. The two personae become greatly embroiled in a relationship with a destitute woman, Marla Singer (Bonham Carter).

While suffering from insomnia, depression, and a split personality, Norton (the Narrator) begins visiting support groups for people with illnesses that he is not afflicted with himself. This induces catharsis within him, enabling him to finally get some sleep.