Opinion: Wellbeing, mood and uncertainty

It is frequently claimed that appropriate lighting can improve the wellbeing of people and change their mood. Such claims should be treated with caution, not because such effects do not occur but rather because such effects are matters of probability rather than certainty. There are three factors that contribute to the uncertainty. The first is simply a matter of definition. The Oxford Dictionary defines wellbeing as being healthy, happy or prosperous. This definition is so wide as to be useless for the identification of lighting effects. There is hardly any aspect of life that cannot contribute to an individual’s wellbeing, positively or negatively. With such a capacious definition it would be a miracle if the visual environment could not be shown to affect wellbeing so something more specific is required to be sure of any claimed effect. Mood is somewhat more closely defined as the way you are feeling at a particular time. This implies mood is a transient state of human emotion. Lighting can certainly influence mood. The second is the possibility of interference from aspects of life other than the visual environment. For example, a restaurant that is attractively lit for a romantic evening will not contribute to a positive mood if the couple cannot hear each other’s endearments. And it is not just the physical environment that matters. There is also the influence of human interaction. Entering a room filled with people one dislikes is likely to darken one’s mood, regardless of the way the room is lit. Mood is inherently labile. About the only situation when lighting can reliably change mood is when it causes visual discomfort. Then the salience of lighting increases and the probability of a negative effect on mood increases. However, very few lighting designers set out to cause visual discomfort. Claims of lighting’s beneficial effects onmood are generally framed in positive terms and it is these positive effects that are subject to interference. The third is the duration of the effect. The positive impact of lighting on mood is likely to be greatest for people unfamiliar with the installation, but how long will that effect be sustained. Familiarity is likely to reduce the impact of the lighting on mood, without any interference from other factors. Therefore, when considering claims of lighting enhancing wellbeing and mood, it is necessary to ask a number of questions. What is meant by wellbeing?What facets of mood are desired?Was mood only affected by the lighting in closely controlled laboratory conditions? How likely are these to occur in the real world? How will the lit space be used? Will people be familiar with the space? And so on. The main point to remember is that the further the outcome is from the operation of the visual system, the more likely it is other non-visual factors will interfere, or, to paraphrase the poet John Clare, the closer to the fountain, the purer runs the stream.