Why it's important to get enough sleep before a race

In this race i figured out the importance of getting enough sleep before a race. I had no major crashes during this one, but i never really got into the rythm at all, and made many potentially dangerous mistakes. I've experienced this before during multiday motorcycle trips where we sleep in tents. The first day usually goes great and i have a blast. Then, in the evening, we sit around the camp fire until midnight. And as we sleep in tents we don't really get a say in when we wake up, so that usually means around six o'clock. Consequently, with only six hours of sleep, i ride much much worse the day after, and i feel like i can't do anything as i bounce around the track.