I welcome your question and appreciate your inquisitiveness. Let me, at the very outset, clarify that it has no religious or spiritual sanctity. It is purely a scientific phenomenon. In this cosmos, we have nine nakshatras and they emit cosmic energy. We live and survive because of cosmic energy. Like all living organism, human body receives cosmic energy, which is a source of regular and adequate flow of life force, eradicates ailments and ensures good health.

This cosmic energy has certain colours. It is something like what you witness in the rainbow. A particular shade of colour is predominant on a particular day. As such, if you wear clothes (more so, for the upper part of the body) of that corresponding shade of colour, then you are in better harmony with nature. You make yourself a receiving station of cosmic energy and cosmic rays enter into your body with more intensity, thus ensuring good health and wellbeing.

If you are in better harmony with nature, then your mind-set, your thinking process, your mental faculties are under your better control. As a result of that, your actions would be positive and better result-oriented. Take for example a situation that you are sitting in an air conditioned room. Your body and mind being in harmony with the temperature and environment, your efficiency level is bound to be high. Reverse would be the case if, on a hot summer day, you are made to sit in a room without a fan. With this background, Param Pujya Guruji recommended wearing the following colours on respective week days:

After sunset, you may wear any dark colour. It should, however, not be construed that only by wearing these colours, one can achieve better results. Nevertheless, it helps you to be in a better state of mind, good health and perform better.