This study sought to study colours and their effects on the human being in order to understand how they work and apply their properties to interior design for a psychology clinic, given that humanisation in the healthcare sector is gradually growing, as it contributes to patient improvement. One of the ways to achieve this is through the use of colour, as it has the ability to provide feelings of well-being for both patients and those involved in the individual's recovery process, if used with knowledge. Without claiming to cure the sick, we are going to use it in Interior Design as an aid to the treatment of patients, who will be diagnosed by the Psychology professional, and who can find in colours an adjunct to this process.