Natural light is both, physically and psychologically, rewarding to people, contributing to our health, productivity, and well-being. Most artificially lit environments have uniform lighting. Light in the natural world, however, is about the layering of light from multiple directions: strong directional light mingling with softer diffuse light, white light with subtle tints picked up from the sky, and reflecting surfaces.
The sensation of brightness is subjective, a relative assessment based on the surrounding light conditions and the conditions we have recently experienced. Our built-in assessment of this perception is an ongoing evaluation, as it is constantly adjusting to suit our surroundings.A person who has spent a lunch hour in a dimly lit restaurant may perceive some areas of the space as being quite bright. Meanwhile, another person walking in from the sunny street outside will see the whole restaurant as being dark. An adequate lighting design should take into consideration a level of illuminance that allows for particular tasks, such as mobility and orientation, to be performed safely. A flow of luminance springing from several sources -being reflected on different surfaces- is what will allow the eye to accurately see and detect.
With true daylight, contrast is what displays a three-dimensional scene, that is, a sense of depth, texture, tone, and dramatic shadows. A well-balanced environment requires filling any dark spots with directional luminaries and building up layers starting from a basic background light.
Creating areas with subtly different qualities of light, provides visual richness to the experience of being in the space, along with the benefits of natural light.