One or more controlled environmental conditions have a characteristic thereof that varies over time at least in part in accordance with a chaotic function. Variable control, for example, may control one or more characteristics of visible lighting of the environmentally controlled space. Examples of lighting characteristics that may be controlled in such a manner include spectral content, intensity, color temperature, chromaticity difference or Delta_uv, and polarization. In addition or instead, one or more characteristics of the atmosphere in the controlled environment may be controlled based on a chaotic function. Examples of atmospheric characteristics that may be controlled in such a manner include temperature, humidity, air pressure, ionization, electromagnetic fields, precipitation, visibility, wind, smell and chemical composition. A sound system may also provide a chaotic component to the environment in the environmentally controlled space.