Take a rest day!
I've often wondered how much fatigue figures into some cycling accidents. In my younger days, I'd ride until I had no energy left. I was a very stuipd way for me to ride. There were times when I had difficulty riding a straight line.
__________________
A conclusion is the place where you got tired of thinking. - S. Wright
Favorite rides in the stable: Indy Fab CJ Ti - Colnago MXL - S-Works Roubaix - Habanero Team Issue - Jamis Eclipse carbon/831