Some of this feels like a bit of a reach to me. Color is very important from a game design perspective in order to help players intuit mechanics - health potions being red, for instance. It’s helpful that gravity magics are all colored purple, which is a hint that they are doing physical damage to magic-resistant enemies such as Rennala. But I don’t think that this means that gravity magic is inherently related to sleep magic as this video claims.

If you haven’t. Try checking out VaatiVidya and Quelaag. I think they capture a lot of the small details very well