Matthew 14:25

And in the fourth watch of the night. The Jews, under the Romans, divided the night, or the time from sunset to sunrise, into four watches, each of them lasting for three hours. And the hours were longer or shorter, according as the nights were at different seasons of the year. At the equinox, the first watch was from six in the evening till nine; the second, from nine till twelve; the third, from twelve till three in the morning; and the fourth, from three till six, or till sunrise. (Witham) --- They had been tossed by the tempest almost the whole night. (St. Jerome)