Simple. There are things to do in the day and essentially parties originate from when people got together to find husbands/wives or just simply to get laid. That's more likely at the end of the day when it's dark later 🙂 So, it's a cultural thing 🙂
At least that's my theory.
And as for suggestion that you need drugs to party all night, that's b***ks though I suppose you could argue that redbull or similar is a stimulant though IME if it's a good enough party, you don't feel tired.
PS I remember hearing that John Smith had died. My first thought was, "what, the guy who does the crap beer?" 🙂