Complex sentence: While under the influence of Joy, Arthur witnesses the town in much brighter and colorful vision, but as it wears off his vision will become more dark and gritty, and Arthur will become more hungry and thirstier.
Split into simpler sentences: While under the influence of Joy, Arthur witnesses the town in much brighter and colorful vision. As Joy wears off, his vision will become more dark and gritty, and Arthur will become more hungry and thirstier.