I always have trouble sleeping before an important event early in the morning, but the night before the race was the worst trouble I've ever had. I got to bed later than I wanted, and after two hours I woke up and couldn't sleep soundly after that. When my alarm went off, I got up and started gathering my things together. My wife came down and asked, "Why are you up so early?" I looked at my watch and saw that I had gotten up an hour early. A few days ago, we had a power glitch, and I had to reset the time on the clock, and I set it an hour early. So, I had about three hours of sleep instead of the four I thought I was getting.
Bruce mentioned earlier in the evening at the Expo that the most important night for sleep is two nights before the race, because it takes a day for our bodies to respond to lack of sleep. I had noticed this with my wakeup heart rate measurements -- lack of sleep frequently didn't affect my resting heart rate for two days.
I felt energetic during the first nine miles of the race, and then I began to feel tired. I have no way of knowing if my lack of sleep increased my tiredness during the race, but it probably did. I think an adrenalin rush was involved, because there have been times when I didn't get enough sleep and felt very tired when I woke up.