I certainly do not think it is an exaggeration to suggest some of the saints may well have suffered from mental illness, or at least some form of neurosis, at one point or another in their lives. Yet many people tend to resist that idea because mental illness has been so misunderstood throughout history. Mrs. Parkes has an interesting post of famous people who have been diagnosed bipolar, which occasioned my reflection upon what saints may have suffered from mental illness, either episodic or long term. The following is my list of candidates of saints who may have suffered some form of mental illness in their lives.
St. Benedict Joseph Labre. Even Fr. Benedict Groeschl says that his namesake was probably psychotic. Of course, that doesn't mean he was a raving lunatic or a danger to himself or others. I suspect he was maybe a borderline personality with bipolar or something. The trials of the dark night would have cured him, I'm sure.
St. Therese of Lisieux. Something was wrong with her when she was little - so maybe she was bipolar too? A couple of her biographers suggested she may have had some early mental illness.
Christina the Astonishing. For sure! She stood in freezing cold water for hours, attached herself to a mill wheel to be repeatedly dragged under water. Astonishing, yes - normal, no way!
St. John of God. His conversion had been so intense he was confined for a time as a lunatic. With counsel, he devoted himself to caring for the poor and destitute, amongst these - prostitutes and vagabonds, whom he invited to live with him. (Imagine the Twilight Zone theme song here.) He endured great criticism and many people continued to think him insane. He went on to found a great order of hospitallers.
Camillus de Lellis. Maybe not nuts - but obsessive-compulsive - and depressive. He was quick tempered and addicted to gambling before his conversion. He also went on to found a nursing order.
Catherine of Genoa. She had to be a depressive - known to be somewhat humorless, she sought escape in the high society of Genoese social life, before entering her deepest depression, which culminated in her conversion. I don't think she was ever fun to be around however. ("Yeah! Let's call Catherine and get together for a drink!" - I don't think anyone ever said that.)
The Penitents, Thais, Mary of Egypt, and other harlots. Thais had a huge public bonfire of her clothes and jewelry before being admitted to monastic life. (Drama is a characteristic of bipolar behavior.) Mary of Egypt... just read about her - not so normal.
The Holy Fools, Basil, Xenia of Petersburg, and others. Basil went about naked in Russian winter and insulted the Tsar, Ivan IV - you know, "Ivan the Terrible". (That's normal.) Xenia was more or less like a bag lady.
Margaret of Cortona. I'm convinced that Margaret went a bit crazy after she discovered her lover's dead body, and the depression which accompanied the rejection she experienced by family and society after her conversion. I'm also of the opinion she wasn't the best mother - she definitely exhibited symptoms of borderline personality disorder in the manner she cared for her son. (I'll bet you anything she called him bastardo a few times.)
These abnormal people give me hope!
[Art: St. Christina the Astonishing, painted by, Cynthia Large]