I wouldn't put much confidence on your ability to accelerate away from a problem, even if you aren't tired. A bad guy can bring you down with a swipe at your handlebars unless you're already well past him. In fact, if you're riding in a deserted area after dark, the bad guy doesn't need to make you stop, he can just jump out at you and grab your handlebars when you're zipping by. By making several laps, you're giving him plenty of time to prepare.

Perhaps the question you are asking is whether you should be riding alone at night.