With everything in life, it's important to eat healthily. The same applies to revision, so here I have a few tips about what to eat in order to get the best results from your revision. Please check out my post about how to revise properly aswell for some more tips
So one of the first things I want to cover here are energy drinks, now these are good if say you've got a deadline for a report or something and you need to pull an all nighter, but when it comes to long term revision, you want to try and stick to a normal sleep cycle, as this helps to consolidate memories and prevents you from being groggy and slow for the next few days (for more see the previous post about sleep). So you shouldn't really be revising really late at night. Also a lot of people tend to have energy drink crashes when they finally stop drinking energy drinks, if you got an energy drink crash in the middle of an exam that could be disastrous, so try to stay away from drinking energy drinks long term (the same goes for coffee).
So what should you eat to keep you awake, alert and energised?
Well the brain only uses one source of energy, glucose, which we can derive from many sources but the best two are sugars and carbohydrates. By sugars and carbohydrates I mean natural sugars and light, slow burning carbs are the best, but sweets and chocolate (dark in particular) are a good choice too, just don't go overboard. Examples of these are pasta, bread and other wheat based products (try to avoid heavily processed foods though) and fruit and veg make a great source of natural, healthy sugars (not sweets and red bull). These foods will keep you full without eating really heavy meals. Try not to eat massive meals but eat a lot of small meals throughout the day, this helps to prevent that groggy feeling you get after eating a big meal and keeps your energy levels more constant throughout the day.
There are also other foods that can also boost your brain's performance, such as fish, leafy green vegetables, berries, milk, nuts, seeds, beans and even chocolate can all help to increase brain function. Supplements are also an option but to be honest the way that the digestive system works means that hardly any of the nutrients actually get absorbed, so it's much more cost effective to eat right instead.
However, probably the most important thing you can do when revising, is drink lots of water. Now it's recommended that you drink about 2 litres or 8 full glasses of water every day, but that doesn't account for individual differences and lifestyle, so what you should do as a general rule of thumb is the obvious, drink when your mouth is dry or as you begin to get thirsty. This not only helps brain function, but helps you feel full and helps to flush out toxins more effectively. You'll probably need to pee a lot more often but the benefits are worth it.
Finally what you shouldn't do is drink alcohol. It can really impair memory as well as cognitive function and of course, if you're hungover there's no way you're going to want to revise anyway. So try to cut down as much as you can, if you absolutely have to drink then try to only have one or two and be sure to eat plenty of carbs and drink lots of water when you get in.
So in summary, don't drink too many energy drinks, don't drink alcohol, do eat fish, veg, fruits, seeds, berries and carbs, have small but frequent meals rather a few massive meals and definitely drink plenty of water.
Good luck :)