Try not too eat too much for the first 3 hours.  The first meal should include a cool, refreshing energy drink or a cup of coffee.  Follow this down with either a couple pieces of fruit, a hearty salad, or some healthier junk food (i.e. oatmeal cookies, biscuits, etc.).  After the first meal, try to eat a little something every couple of hours to keep your energy supply up.  Plus, this should keep you going as it will be a great incentive.  Can anyone say "Scooby Snack!"  

It is important to get rid of all distractions and focus on your task at hand.  Wearing pajamas, slippers, and sipping on some hot cocoa in a dark room while listening to classical music on your bed is not your ideal situation.  Here is a quite check list when embarking on your all-nighter:

• Turn on all of the nights  
• Put on some nice, non-snuggly clothes
• Put on some upbeat music with no words - too distracting
• Find an upright, non-cushy chair
• Do not even go near the TV
• Find a desk with a whole lot of room
• Find a quiet place with no distraction

If you adhere to the above list, you will greatly increase your chances of focusing on what you gotta do.  

Write an outline of your time schedule, and what you will do at every hour.  If you have notes available, then you have a basic schedule already outlined for you.  Four example:

You get the idea.  Knowing how you get from beginning to end will give your assignment some much needed order.   If you cannot make your time table, then skim over the rest of the chapter or briefly finish your paragraph, and get onto the next section.  You can always come back and finish the undone segment later.  Teachers are always more impressed with a completed document than one that is not grammatically or structurally perfect.

When you are studying for a test, make sure you take notes as it will help your short term memory for crunch time later in the day. 

You need to find something that drives you on.  Dressing into your pajamas and slippers will get your mind more on your bed and what you are missing than on your studies.  Try to stay out of your room, and preferably in an uncomfortable chair that will drive you on to finishing your assignment quicker.

Stressing out and thinking that you will never get it done will only waste precious seconds.  Relax, take a deep breath, and dive right in.  You will look back on your University all-nighters with fond memories and remember the "good ol' days."  Enjoy it, because you won't have these adventures forever.

Anyways, if you give in to studying in your bed, you will quickly find your self drooling on your assignment that is due in the morning.  Thinking about your bed occasionally is not a bad thing as it will give you a major incentive to not procrastinate and finish as soon as possible.