To meet the legal definition for insanity in most countries, a person must be incapable of telling right from wrong. By that definition, was France's King Charles VI insane? Maybe. Was he mentally ill? Unquestionably. With only the benefit of medieval accounts, it's difficult to make a diagnosis, but Charles VI did have psychotic episodes throughout his life, beginning at age 24. His episodes lasted from three to nine months, and recurred about every three to five months until his death. His contemporaries reported that the madness started after a mysterious disease caused his hair and nails to fall out.
By all accounts, when he was "himself," Charles was a gentle and kind man. However, when in the throes of an episode, he was paranoid and aggressive -- even to the point of murder. Some modern historians have theorized that Charles may have been schizophrenic, which fits with some of his behaviors and the age of onset of his symptoms, but this is simply a theory. He may also have had encephalitis, which could have brought on the episodes. At one point, he went through a phase in which he believed he was made of glass and asked to be wrapped in blankets so he wouldn't break. Charles VI died in 1422 at the age of 53, having ruled France for 42 years.
Other facts about Charles VI:
"Was France's King Charles VI Insane?" He certainly was. Nobody would ask that question today.