User blog comment:DancePowderer/Aokiji Vs. Akainu, Part 6/@comment-4904935-20130320033533/@comment-1595565-20130320052307

Yeah, it never said. For all we know they stayed awake out of sheer willpower and didn't notice how long they had been fighting. Jinbe did say they were both exhausted and heavily injured by the time the fight was over.