I stayed awake for almost three days working on a visual effects project once. In class the third day, I got sick and my professor literally forced me to go home and sleep. It is a terrible terrible feeling. ;A; It can be quite harmful to the body to pull more than one all nighter. I completely understand your situation this time, though. However, you should do your best to get some sleep tonight =)
I just had a string of days where I wasn't able to sleep for more than three hours. No reason apart from insomnia really, which is what pissed me off about it, since it would be understandable if a late night cramming for finals session is what did me in, but no, I just couldn't fall asleep. But basically, after five days of this, while I was driving home I just got really dizzy and started having auditory hallucinations, so I actually had to pull over and chug 16 ounces of coffee before I was able to make it home and have a nap before evening classes. Was not much fun, I can say that ;.; tl;dr Get your sleep on, kids.
Do you really need to stay up to watch the casket? I remember falling asleep on the benches near the casket during my grandmother's death. (everyone did actually)