Actually, in the movie, Sandman is the Guardian of Dreams... He protects every child at night when theyre asleep... He makes every wish of every kid come true throuh his dreams... He is the busiest guardian coz he has to give beautiful dreams to every child in the world 24/7... And we all know that there's always night on each side of the earth so technically, he has no break...
The Rise of the guardians wiki said "Sandman is the Rise of the Guardians re-imagining of the mythic bringer of dreams. He is the first ever Guardian, the Guardian of Dreams. He lives on a island. It appears that he is Pitch's true enemy, and really the only one that he is afraid of. Sadly, in the movie, he is seemingly destroyed when Pitch turns him into a nightmare, but he returns at the end, using a dreamsand whip to defeat him once and for all. "
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