1) There are two reasons for the obligation to wash one’s hands in the morning: A) because while sleeping he will have touched the covered parts of his body for which one is obligated to wash one’s hands. B) Given that in the morning we are made like new creations, and we thank Hashem Who created us to honor Him, to serve Him and to bless Him, Chazal therefore decreed that in the morning we should make ourselves holy with His holiness and wash our hands with a vessel, like a priest who washes his hands from the Kiyor (water container in the Beis Hamikdash) before serving in the Temple. (Shulchan Aruch and Mishne Berura 2)
2) The halachah is that we worry about both of these reasons and therefore even one who sleeps during the day or stays awake all night must wash his hands. (Mishne Berura ibid)
