There are numerous signs that Willy Loman is mentally unhealthy and unstable throughout the play.
The first sign that Willy Loman is mentally ill takes place when he admits to his wife that he almost crashed his car again because he could not stop daydreaming while he was driving. Willy's inability to remain focused on the road is highly concerning. Despite his failure to drive and comments that indicate he is completely exhausted, Willy holds onto the hope of attaining the American Dream. Although Willy is an unsuccessful salesman who cannot pay the bills, he firmly believes that he can still attain the American Dream, which is rather disturbing.
Willy's contradicting statements about his occupation and son also raise concerns about his mental health. Another sign of Willy's unhealthy mental state is the fact that he has a rubber hose and has been contemplating suicide.
In addition to Willy's thoughts about committing suicide, his constant hallucinations and inability to differentiate the past from present reality are also signs of his diminishing mental health. Willy continually speaks to his deceased brother and represses painful memories. He has difficulty remaining present during conversations and his thoughts constantly return to the past. Willy's inability to accept the reality of his situation also raises concerns about his current mental health.