According to Suetonius in his Life of the Deified Julius (45.1-3):
"Caesar is said to have been tall, with a fair complexion, shapely limbs, a rather full face and keen black eyes and to have had sound health, except that towards the end of his life he was subject to sudden fainting fits as well as nightmares. He also had two attacks of epilepsy while on campaign.
He was fastidious in the care of his person and so not only kept his hair carefully trimmed and shaved, but even had his body hair plucked. He was extremely vexed by the disfiguring effects of his baldness since he found it exposed him to the ridicule of his opponents. As a result he used to comb his receding hair forward from the crown of his head and of all the honours voted him by the senate and people, there was none that pleased him more or that he made use of more gladly than the privilege of wearing a laurel wreath on all occasions.
They say too that his dress was unusual; his purple-striped tunic had fringe sleeves down to the wrist and he always wore a belt over it, although it was loosely fastened. This it is said was the reason for Sulla's frequent warning to the optimates to beware of the 'loose-belted boy'."