Feng Shui says soft light creates a positive energy and the right conjunction of light, which is colour and direction promotes harmony and prosperity, relating it to the yin and yang symbol of harmony, where you need both.
In Vastu Shastra, colour, light and smell are often used to remediate inauspicious conditions in existing structures. It’s a fact that is probably known to all of us, and, it is encouraged to turn on all the lights in house at night, even briefly to expel all negative energy, I know lot of us are made to do that at Diwali so that Lakshmi comes and everyone’s got money, but I’ve had several friends who’ve come and said, “Yeah, my mother used to make me do that”. And, then there is of course the famous shloka from Rig Veda which is, “Asato ma sadgamaya”, and then, “tamaso ma jyotirgamaya.”
Somewhere along the line, in our culture, darkness became a bad thing, because darkness was seen as ignorance or lack of awareness, and light was seen as knowledge. Then, in the Jungian philosophy, it says the shadow is the reservoir for human darkness, as well as the seed of creativity. All of us creative people are really, according to Carl Jung, relying on the shadow in some ways. And then Sufism on the other side says, “Nothingness, which is darkness, is essential to attaining enlightenment”.