Caligula and Nero are two of Rome's strangest emperors. Within both of their reigns, they both did very weird, even insane things. Of course, arguing over the sanity of people that lived almost two thousand years ago is futile at best. There is just no possible way to know for sure whether they had mental deficiencies or anything of that sort. However, while looking at the deeds of both of these emperors, one can do nothing but suspect the position almost required a degree of insanity.
Almost all accounts of Caligula and his rule as emperor contain elements of madness, cruelty, extravagance, and things of that sort. In several sources it is noted that Caligula was quite insecure of his hair, or lack thereof. In fact, it was a capital crime for someone to stand above him and look down upon his head. Also, he sometimes ordered those with a fine head of hair to be shaved. He made up for lack of hair on his head by an abundance of body-hair. About this too he could be equally sensitive; even the mention of "hairy goats" in conversation was dangerous. He used to grimace, which he practiced in front of a mirror, and he was an impressive orator.
Though he acted very strangely in his later career, Caligula started out just as almost any other man would have. He grew up in a camp as a favorite of his father's soldiers. The troops nicknamed him "Caligula" after the child-size military boots he wore in camp. From the Emperor Augustus he inherited ambition and sensuality as well as the family affliction epilepsy. He was caught in bed with his sister Drusilla before he came of age. His famous father Germanicus, his mother Agrippina the elder and all his brothers were either killed or starved to death by order of the suspicious Emperor Tiberius and his ambitious Praetorian Prefect, Sejanus. During his adolescence, Caligula was a virtual prisoner of Tiberius. By then Tiberius had largely withdrawn from active government and retreated to the island of Capri, where Caligula kept him company and tried to play the part of a dutiful and upright young man.