Have you ever felt like you were actually going to die?

OK I might seem like I'm exagerrating but I actually felt like I would die. I have a very busy schedule and so I barely get enough sleep or even have time to eat. So this afternoon by 5 pm I had only eaten once in two days. And gotten like 8 cumulative hours of sleep. That should've been OK at least to manage but I felt dizzy, weak and like I would faint at any moment. And whenever I was 'falling asleep' while in the staff bus I'd feel like I'm about to drift into some sleep that I'd never wake up from so I didn't sleep. To add to it all since my friend died a few weeks ago the tiniest things have made me just think of death. Because my friend's death was very unexpected, he was healthy on a Tuesday afternoon and he died on Friday of the same week. Even now its midnight but I just can't sleep because Im worried that I'm going to die