Night had fallen. The Fathers of the Church saw this as an expression not only of the time of day, but of the state of Judas’ soul. But this darkness refers also to the whole situation. Heavy black shutters have slammed down over the heart of Judas. The disciples too are finding themselves ever more heavily curtained off from understanding what is happening around them, and from help, increasing their growing anxiety.
Even Jesus is not immune. The darkness is dripping now like a heavy black ooze over Jesus. All is becoming black, as Satan tries, and the Father allows, the Light of the World to be extinguished.