With the days getting shorter up here in the northern hemisphere, I am forced to run at night. I live near a major city, and am concerned that automobile drivers won't be able to see me that well. What can I do to make my presence on the road more noticeable, for safety's sake, while I am running outside in the dark? - Night Runner
Deep within the darkest depths of our planet, seven miles below the surface of the Pacific Ocean, there exist creatures that glow with their own bio-luminescence; a useful defense mechanism against light sensitive predators. Several species of squid have their lower bodies covered with photophores, which emit a soft glow when activated. These creatures remain in the darker, deeper parts of the ocean during the day light hours, and come up to the surface at night under the cover of darkness. Squids use their bioluminescence as a counter-illuminator. Predators hunt by looking upward as they swim, searching for a shadow or silhouette. Some squid activate their photophores to match the light coming down from above, making them invisible to the attackers down below.
Runners are a species that requires luminescence as a defense against their own predators: automobiles. While battery powered wearable lighting devices, and highly reflective material clothing helps to make runners shine in the headlights of oncoming vehicles, it is this runners opinion that there has got to be a better way. Batteries lose their power, and reflective clothing can loose their luster, but as our friend the squid can tell you (assuming they had the power of speech) bio-luminescence is forever!
My advice to you is to turn to science. Recently, genetic bio-science has mapped the entire human genome. This gives mankind the ability to create some very useful accessories and features to the human body, previously made exclusive to other creatures. Somewhere in a laboratory, scientists are figuring out how to give humans webbed feet for swimming, wings for flying, a kangaroo pouch for carrying stuff, and gills for breathing underwater. But wouldn't it be great if we had glow-in-the-dark skin? Imagine how useful it would be to emit a powerful "glow" from our own bodies while out on the road each night!
Others might argue that your best defense is a powerful offense, and that wearing a high intensity halogen-based million candlepower head lamp will effectively blind any oncoming vehicle, enabling you to dodge their offensive attack on you as you are running at night.
Of course, it is important to always run in a direction traveling against the normal flow of traffic, and never assume that because you can see an automobile, that the driver behind the wheel can see you. But I think bio-luminescence is the true solution to your problem; but reflective clothing and a headlamp are probably good first steps while we are waiting for the guys in the lab.
Run long and taper.