For many years light was simply reduced to its basic function: providing brightness to enable vision-related tasks to still be done even after dark. Now it has been recognised that light has a tremendous influence on people and their health. Light significantly determines our well-being, it controls our sleep / wake patterns and during the day it regulates the release of a wide range of hormones. Against this background modern lighting technology now enables the targeted use of lighting in hospitals, offices or schools for example where it has a significant impact on our recovery, performance or levels of concentration.

The third type of photoreceptor – light controls our internal clock
The very fact that this is possible is owed to a discovery made by researchers only around 10 years ago. In 2002 in addition to rods and cones they found a third type of photoreceptor in the eye, the so-called ganglion cells that are distributed across the retina. What is unusual about these cells is that they have no part of play in our sight. Instead they are connected directly to an area of the brain that controls our ‘internal clock’ and attunes our body and its metabolism to the activities of the day and night-time rest. Research has established how daylight in fact affects our body with our performance declining at midday, our sensitivity to pain increasing during the afternoon and our short term memory working best in the morning. Today’s industrialised society life is characterised by a fixed time pattern and as a rule people are not able to follow their natural biological rhythm. As a result lighting solutions are required that have a positive effect on the rhythm of human existence.

The effect of dynamic lighting
The workplace is an area where today the biological effects of lighting are of particular interest and its use is increasing. So-called daylight architecture is based on the most intensive possible use of natural daylight to which artificial light is then added when it is required. Conversely in rooms or buildings when there is a low incidence of daylight it is possible to simulate the natural process of daylight using modern light bulbs and light-management systems so as to reproduce the same biological effect. In the morning the addition of a blue component serves to motivate, while a light-blue light in the afternoon promotes concentration and softer lighting with yellow and orange tones accompanies the end of the working day. Studies prove that employees sleep better and are more productive during the day and this is often accompanied by increase in general well-being, which of course in turn has a beneficial effect on work and motivation.

Such lighting solutions having a so-called biological impact are also used of course in the fields of health and education. An example is the use of dynamic lighting as part of a study in a rest home for the elderly in Austria, where the majority of residents had dementia. These people often have irregular sleep / wake patterns and tend to pace up and down the whole night long. The researchers employed a lighting solution which is able to run a sequence of lighting scenarios in terms of light intensity colour temperature. The results: depending on the mood of lighting the residents were more attentive, more communicative and more active. In many cases activity during the day also normalised sleep / wake patterns and as a result the use of sleeping pills was reduced. Another study carried out at a school showed that dynamic lighting in the classroom was able either to promote concentration amongst the pupils or had a calming effect.

Attuning light management to people in the ‘LifeCycle Tower One’
In this case it not just a question of the brightness or the colour of the light. The angle of incidence, the dynamics and the ratio of direct and indirect light are also critical factors in effectively reproducing the natural course of daylight and the biological effect of light. An innovative office building in Dornbirn in Austria shows how in practice you can attune dynamic lighting to the rhythm of human life. The LifeCycle Tower One’ is the first eight storey hybrid house made from wood in the world: while the wooden support structure is visible from the inside, the exterior skin consists of aluminium. As befits a sustainable method of construction an intelligent light management system has been installed. A sensor to measure daylight on the roof of the building calculates the exact incidence of light. The system uses this to individually control when artificial light is required in each room. Previously defined lighting moods can be retrieved in terms of the colour and quantity of light, while the installation of movement detectors in the building promotes energy saving so that light and heating are only activated when they are actually required. Indeed in addition to the positive effects on people, this maximum use of daylight also enables a not insignificant energy saving. As a result the additional costs for the installation and design of a dynamic lighting system are amortised in a comparatively short time – and not least also thanks to more motivated, more productive and healthier employees.

‘Light and health’ is one of the main themes at the forthcoming Light + Building from 30 March to 4 April 2014 in Frankfurt am Main. This is the world’s biggest trade fair for lighting and building technology. In addition to LED / OLED lamps and innovative new lighting technology international manufacturers will be showing systems for the intelligent control of lighting that provide the very basis for dynamic lighting attuned the needs of people.