As early as age 7, Gilgan was diagnosed with hyperactivity and dyslexia, which caused him to have trouble recognizing words accurately and quickly, as well as writing. To reduce the symptoms of the disorder, Joseph was sent to a drama studio, where teachers quickly noticed his talent. However, the problem did not go away, as his parents soon divorced, and as a teenager Gilgun even had to take antidepressants. At 26, the actor was diagnosed with another disorder, this time bipolar. It is manifested by frequent mood swings, periods of depression. Because of multiple mental health problems it was especially hard for Gilgun to make new relationships. Throughout his life, he has had just a few friends. Joseph isn't' active on social media, but is happy to do interviews and communicate with fans. The actor has more than a dozen tattoos. He gets a new one every time something big and important happens to him. During the filming of 'Misfits' Gilgan was the only actor who did not need fake tattoos: he had enough of his real ones already.