Laura Hancock - Interpretations of light

As I was reading "Sacred Landscapes and the Phenomenon of Light", the question of why we relate darkness to death occurred to me. Darkness is mysterious, just as afterlife and death are to people. Light means a clear image, and this present life is clear to us, or at least clearer than the afore mentioned possibility. People also associate darkness to evil, though, but death isn't necessarily associated with evil. In fact to many people, death is connected to heaven and release from pain, so why is darkness regarded as a bad thing to so many people?