Wow, so, sleeping late does cause more breakouts. For me, it basically boils down to the bacteria trapped in my face. So make sure to wash your face no matter how tired you are to do so! Also, both my parents had LOTS of pimples on their face and back during their teenage years and that may have something to do with me having the same case.

The food that you eat that matters the most too.

STRESS! Even it's vacation, there still so many things that stressing me out LOL PLUS the pollution, when dust and other free radicals enters our pores, well that's the start of our battle with our enemy. THE PIMPLES. ;D