dunno--it's Ramadan then, isn't it? Well, how hungry do you get during the day? (if you're one of those hardly-hungry people like me, you'll survive the HSC). I guess you could always apply if it will affect your HSC performance significantly, though as Cape said above, if you have determination, you will succeed no matter what. Ask around or phone the relevant people up (I dunno what the number is) and see.