I once had very minor dental work done. NO2 was involved. I waited a little while after, to make sure I was ok from the gas and proceeded to drive home. I felt great until all of a sudden I realized that the lane I was driving in closed in about 30 feet, and I was doing 40. It's a good thing I was driving the sports car, not the jeep, or I never would have been able to stop in time. Point is, I felt great, but it took me an entire 30 seconds or so for it to register what all those silly signs on the side of the road telling me to merge left really meant. Scared me so much I called my dad to come pick me up and take me home. Imagine if someone in front of me hit their brakes and it took me 30 seconds to realize what THAT meant.