This may seem crazy, but think of it for a sec. When you point a light directly on the surface of your skin in a low-light environment, it is actually way easier to find veins, especially when you are trying to search for the right one. Try it yourself, it works even with your phone flashlight. As a matter of fact, why don’t nurses spot-light the flesh first in the obscurity, then insert the syringe or any other tool with a needle tip needed?