How the colours of objects and light affect human emotions, performance and health. The need for a holistic approach to design indoor environment.

Colours and lights have been shown to influence mood and performance, "cool colours" like blue and green are relaxing and peaceful to the eye, whereas "warm colours" such as red and yellow seem activating and arousing. Cool light, rich in short wavelength radiations, has also a significant effect in terms of circadian rhythm synchronization by inducing melatonin suppression.For colours to be used in industrial objects, social and cultural factors also play a significant role.The choice of colours in indoor environments, for both objects and light, should thus be done considering all these aspects. However, these different approaches lead to different points of view and to hardly comparable results. Also, the design process is unique and the final user is not able to distinguish between colour perception,visual and non visual effects of light as well as messages that can be expressed by means of colour patterns.It appears necessary to establish reciprocal interactions among the different disciplines involved in the choice of objects and light colours, and namely among researchers in medical science, psychology, lighting and industrial design, in order to assess an interdisciplinary methodology that can be applied to indoor desig