I always suffer from nerves the night before and morning of an event. Stupid really as I can crank out similar rides in training with monotonous regularity. But add in a race number and a bunch of amped up strangers and I go to pieces. A decent warm up ride seems to help somewhat.

As long as you are getting plenty of sleep most nights, it won't affect your cycling performance too much to only sleep lightly the night before an event.