The answer is "really badly." There are several drugs to treat ADHD that students are taking to improve focus and study all-nighters before exams. But, this is a really unhealthy use of those medications. You most probably will eventually crash (as you would say) because you have to. This is your body's way of recovering from the damage you are imparting on it by skipping sleep. It is clearly not a sustainable effort. Human beings do need sleep for body repair, cognitive function and learning (yes sleep plays a key role in encoding information you have learned during the day).
I am not sure the long term effect of taking ADHD drugs for adults regarding impact on sleep has been studied. This is probably because ADHD drugs are typically not aimed at adults to begin with, but to treat children with ADHD. There has been some studies regarding ADHD children (medicated and unmedicated) and their respective sleep patterns vs control groups. And, the results are not entirely conclusive as expressed in this one study.
The above, nevertheless, should not give one any comfort that using such ADHD drugs over the long term as adults to reduce chronically sleep requirement is safe. That's for a simple reason, attempting to reduce one's sleep requirement is downright unhealthy and dangerous by itself.
However, human beings differ. A rare minority of the population (1% or 2% of the general population) are called "short sleepers." These fairly extraordinary individuals can fare very well with much less sleep than the rest of us (probably half the requirement or close to 3 or 4 hours a night instead of the regular 7-8 hours). Unless, you are a true short sleeper any effort to cut on sleep is not a healthy idea.