Roadtrips involve peaks and valleys of tiredness and alertness. I always stop when I'm started to feel tired, get out of the car and walk for 5 minutes, and usually feel pretty good. I'm often weariest in the late afternoon and then most alert during the evening hours, although I get tired after about 2 hours of night driving.

Roadtrips often involve abnormal food/bev intake. Throwing caffeine and processed carbs into your body in unusual quantities and at weird times probably messes with you a bit. But what else are you going to do when your dietary choices are the Flying J and Travel America?