Most historians agree that epilepsy is the most likely candidate for Caligula’s disease. There are several details in Caligula’s biography that support this argument. It is suggested that members of Julius’ family suffered from epilepsy. Additionally, several historians point out that during his childhood, Caligula had episodes of sudden falls during which he lost consciousness and had difficulty staying upright. Analyzed from a modern perspective, these episodes may indicate atonic seizures.
Moreover, Caligula sometimes had a fever, a symptom that accompanies the onset of temporal epilepsy. Rare childhood episodes may not necessarily be evidence against the epilepsy theory, as people with epilepsy can lead normal lives during interictal periods.
As for the origin of Caligula, it is possible that in 37 CE he experienced status epilepticus, which left him with emotional, behavioural and cognitive aftereffects. After this episode, he exhibited constant mood swings with irritability or unmotivated laughter, lack of impulse control, perverse behaviour, hypersexuality, and sadism, and was terrified of thunder and loud noises. Caligula also suffered from severe insomnia and could not sleep more than three hours a night. Moreover, he experienced delusions of grandeur, and paranoid episodes, and exhibited strange behaviour such as when he ordered his soldiers to collect seashells from the seashore.
All these symptoms fit into what is known in modern epileptology as epileptic psychosis. The condition has a prevalence of 5.6 to 5.9% and can occur with any type of epilepsy. However, its incidence increases to 9.3% in people with temporal lobe epilepsy. One of the first symptoms is insomnia, which is often mentioned in accounts of Caligula. Epileptic psychosis can also be characterized by symptoms of depression, delusions, manic psychosis, strange thoughts and behaviour.
It is likely that Caligula suffered from epilepsy that began in childhood, perhaps with febrile seizures, and later dialeptic or cognitive. In 37, Caligula experienced a state of epilepticus that triggered an epileptic psychosis followed by psychopathic and paranoid changes. This clinical condition could also be influenced by excessive alcohol consumption and lead poisoning.