Getting enough sleep is very important on many levels. When we are young we often ignore the importance of sleep because we feel there is just so much to do, and so little time to do it in. Yes, life is short, but without knowing it, you may be shortening it even more by depriving yourself of sleep.
Studies have revealed that sleep deprivation can be linked to increased blood pressure, increased risk of diabetes, increased risk of fibromyalgia, seizures, obesity, aching muscles and depression, to name just a few.
Depriving yourself of sleep to study for exams is probably the most counter-productive thing you can do. Among the many consequences of sleep deprivation, its effects on attention and working memory are perhaps the most important. Strangely enough, sleep deprived people have a better short-term memory than rested people, but if you are sleep deprived your brain has to work much harder to even access working memory and logical reasoning.
If you are greatly sleep deprived, your behavior can mimic that of psychosis. This is because a lack of sleep prevents you from making an appropriate evaluation of emotional events. In turn you will react to these events inappropriately. Emotional over-reacting or seeming emotional 'bluntness' are symptoms displayed by psychotic patients.
If you don't want to come across as psychotic, and you desperately want to pass your exams, it may be a better idea to not leave things to the last minute, and to get a good seven to eight hours of sleep at night.