Half practicality, half aesthetic; the top knot is the pinnacle of laid-back hair. I don’t know whether your climate actually lends itself to making this look work, but it’s certainly something that could not be pulled off quite so well in England! I even subconsciously started wearing my hair like this when I first arrived here.
Tip your head upside down and pull your hair into a messy bun using a hair elastic (the messier the better). This is also a bit of a model trick for disguising over-styled hair from a shoot on the (occasionally humiliating) journey home.