I understand you may think its a long time, but you're looking at it wrongly.
Being able to stay out for long periods requires years of practice. I'm not joking either.
I was once like you. Go out, home chilling by dawn. Nowadays if my body has sleep Saturday, it just doesnt feel right, like I'm ill or something.
When I got back from Uni in Brighton (where all clubs shut at 4ish) I started hanging around with all my old school pals back home, people who took things a little more professionally. (You're surrounding people play a heavy part in your training. You cant do this alone).
First of all, you need to mentally rip up your calenders. Sunday no longer exists. Your week goes Monday, Tuesday Wednesday, Thursday Firday Saturday, then back to Monday. Thers still 12 months, 365 days, 52 weeks a year, BUT only 6 days in a week.
As I said before. The ability to stay out for days on end does not come overnight. Imagine what it takes to run the London Marathon. This is the same.
During your training, its all about mental will power. You need to focus your mind on a late finish. Say from Saturday night, EVERYONE first time round, should be able to make one big night out followed by the initial stages of the afterparty. Target the fact that when you go into a club you CANT leave until it is light. The first afterparty is always the hardest.
Remember, you've got to be out for days, so its no point going ape in your first club at 1am. I don't normally get going til 4ish on a Saturday. From midnight til 4, thats my sociable time, meeting new people and catching up with old faces in the club. My 'bar' time. if you will.
Now the thing is with afterparties, that they are normally split in three. The first bit, your reflecting on how the previous club was. Then, for a very short period, your enjoying the afterparty as a clubnight(day) on its own. Then its the best stage. The frantic discussion and expectation of whats happening next. This is the sort of cycle to get into. DO NOT STAY FOR THE LAST SONG. Not only will there be that general sense of 'nights over, lets go home' but you need to get to the next party and not queue for hours.
This sort af behavior cant happen in most towns. Ibiza was MADE for this kind of tactic, and Londons pretty well suited for this.
I'd just like to add that this IMO is not possible without our chemical sidekicks. If you are not prepared too do these in, quite frankly, ludicrous amounts, then you are doomed to faliure. You need to build up your resistance for this. I wont go into further details here, pm me for more advice.
I'm not saying this sort of thing is easy, but its worth it in the end.
You, too, can be a part of clubbing folklore.