At first glance, this may seem a lot, but it is understandable when you consider that our eyes form our main contact with our environment – from morning to night without a break. Good lighting is therefore more important than we generally assume.
In recent years, human biologists, general practitioners and psychologists have increasingly looked at the effects of light on the human organism and psyche.
Within the scope of the FVLR-initiated project “Using Daylight”, it was proved that human health is affected by light far more than was previously known or suspected, because light is an elixir of life.
You can watch a 2005 lecture on this – “Ganzheitliche Lichtbiologie” [Holistic Light Biology] by the general practitioner A. Wunsch, which he delivered at the 2nd NetzwerkForum congress.
The artificial lighting of workplaces is one of the major causes of “sick building syndrome” (SBS); however, illumination via daylight positively affects the health even if disruption occurs (e.g. warmth entering the building or glare due to poor planning). People who work in unfavourable lighting conditions feel tired sooner, get more headaches and/or suffer more frequently from a lack of concentration. The further away from the window a workstation is, the worse these problems are.
However, it is not only the lower light intensity which has a negative effect on humans – the remaining spectral composition of the artificial light emitted also effects people in a different way to natural daylight.
The lamps and lighting industry is trying to compete, with so-called “full-spectrum lamps”. What this term means according to the Ergonomic-Institut Berlin can be downloaded here.
Winter blues, also known as “Seasonal Affective Disorder” (SAD), also arise as a result of insufficient light. This illness is not a rare one. It is estimated that about a quarter of the population of central and northern Europe are affected. Winter blues can be easily and very successfully treated with natural light.
Conversely, it should be noted that the effects of a lack of natural light lead to ailments in the human body. The history of rickets and its connection to a lack of light is a further example.
Currently, there is discussion as to the effect of light on the development of breast, colorectal and prostate cancer. It has been noted that these carcinoma disorders have a geographical correlation. It has been demonstrated that the survival rate for breast cancer is higher in places where people get more sunlight. One effect is on the body’s production of melatonin, which is significantly influenced by light. The hormone melatonin controls the human sleep-awake rhythm (circadian rhythm). Artificial lighting interferes with the natural melatonin production, if used during the hours of darkness. This effect furthermore causes a reduction in the production of oestrogen in women, which in turn leads to an increased risk of breast cancer.
The circadian rhythm is determined primarily by daylight. Every day, it ensures that our inner clock is reset. The ZDF-heute team have made a video about the functioning of the internal clock and the serious impact on people. You can view this video here.
The impact of light on humans goes far beyond these examples, however. Studies to date have shown, for example, that light also
- has a positive influence on blood composition,
- suppresses melatonin production (the sleeping hormone),
- allows “good-mood hormones” such as seratonin and noradrenaline to take effect,
- increases performance,
- improves the immune system,
- positively impacts hydration,
- has a positive influence in combatting septic diseases,
- has a positive effect on ear, nose and throat illnesses,
- allows the synthesis of Vitamins A and D,
- regulates the metabolism,
- has a positive influence on the activity of the adrenal cortex and
- has a positive influence on skin diseases such as acne and psoriasis.
The absolute uniformity of working conditions was being discussed as far back as the 1970s, when large offices were being built. It was said that humans should be able to do their work undisturbed by adverse factors. So the environment created was not only of a nice temperature, but also illuminated the same throughout. The ultimate aim was an increase in productivity.
However, on closer inspection, it was seen that the same means deployed by the experts to rationalise work had also been applied to breeding chickens. Even a well-founded and much-cited 1954 publication in the field of lighting technology by the director of the University of London Institute for Ophthalmology was not able to change much initially.
The institute’s director, Mr Weston, wrote:
“Having different brightness distributions and different brightness levels is considered to be tiring and somniferous. In order to prevent this, visually-stimulating changes in the environment are being avoided. But change is more than just the spice of life – it is an indispensable condition of conscious life.”
The change in the visual environment is provided by natural light without any further action being required.
Whereas in the past we tried – without success – to sideline the dynamics of the daylight as much as possible, we now try to recreate them artificially.
Weston, once again:
“Proponents of engineering brightness, which is currently in fashion, have recommended that ideal conditions for seeing prevail when the field of vision is of uniform brightness. There is nothing in human physiology which supports this idea. (...) Artificial lighting has an inherent, undesirable property. Although its constance is a much acclaimed property, and implies the superiority of artificial lighting over variable natural lighting. However, even though constant conditions are desirable for some critical visual tasks, constance is a soul-destroying and stupefying property of artificial lighting.”
Weston's message was however ignored for half century.
Behaviour, learning, achieving
According to an Australian study, children may be spared short-sightedness if they spend extended amounts of time outdoors every day. Researchers from the Australia Research Council discovered that eye growth is regulated if the eyes are exposed to bright light for two to three hours a day. This dramatically reduces the risk of short-sightedness.
Getting sufficient natural light improves the behaviour of school, both in terms of increased concentration and an improvement in their social behaviour. It is reported that children with attention deficit disorder (ADD) achieve more when subject to daylight than when subject to neon lighting. This is supported by a study of Swedish children's behaviour, conducted by measuring levels of cortisol (a stress hormone), in classrooms furnished with daylight. The results suggest that working in classrooms without daylight upsets basic hormone patterns, which in turn influences the ability of students to concentrate and cooperate. This also has an impact on annual body growth and days off due to sickness.
According to several American studies, sufficient natural daylight – and specifically light coming into rooms from above through skylights – improves children's learning in a school context.
In-depth studies from the world of work also demonstrate less tiredness in better illuminated workplaces, and consequently a fall in the rate of sick days drops, and a steep rise in the productivity curve.
The Ilmenau University of Technology investigated the correlation between performance and illuminance at some typical industrial workspaces, in nine to twelve test subjects.
For difficult tasks, such as the cutting of workpieces, higher illuminance leads to a significant increase in performance. This increase was as much as 150% where 600 lux was provided instead of the prescribed nominal illuminance of 300 to 500 lux.
Proper lighting not only makes your working day easier, but also helps to ensure fewer errors – which is an important economic factor.
So investment in light as a “productivity factor” is always worthwhile.
Communication and sight
Daylight improves visual performance, although visual performance is a measure which has not been defined with sufficient precision. In the field of lighting technology, it is understood as meaning the recognition of shapes and contrast. In doing so, the eye's visual system is called upon in terms of visual acuity, contrast sensitivity and shape sensitivity, as well as the speed of perception and adaptation to distance. The eye's performance depends greatly here on the luminance level, which is determined by the “intensity” of illumination cast on the viewed object. It is for this reason that most technical light specifications focus on illuminance. This is also reflected in the provisions of the relevant standards. However, this approach has several drawbacks:
- Illuminance as an integral measure determines the luminance of the lit object only if it is flat and completely matt. This is not normally the case in our living and working environments though. If a viewed object does not have a matt surface, then light coming from a certain direction may reduce or even negate the effect of light from another direction.
- When calculating illuminance, it is irrelevant whether the light comes from a large area with relatively low luminance (e.g. a skylight), or from a smaller area with correspondingly high luminance (e.g. artificial lighting with modern energy-efficient lamps). The impact on vision are great, however: The risk of a direct or reflected glare onto illuminated objects is much greater for small light sources with high luminance.
- The recognition of the colour or shape of physical objects unfortunately does not make it into any definition of “visual performance”. For this reason, the increase in the light yield of modern energy-saving lamps is based on a physical trick. Namely that the increase is compensated to a considerable extent by a worsening of colour rendition.
So what is commonly referred to as “visual performance” leans heavily on a few elementary functions of the eye, to the detriment of other important functions, e.g. colour recognition. In order to realistically compare daylight with normal artificial lighting, we should evaluate the costs of artificial light at approximately 60% higher, solely to take account of the colour-rendering properties.
And if we wish to compare roof skylights with artificial lighting within the sense of the eye's overall performance – including the recognition of shapes and including reflected glare – we should make one lux of daylight equivalent to two lux of artificial light. That is to say that with daylight, you need roughly half the illuminance to achieve the same visual performance.
If you then take into account the fact that light is always connected with the inevitable accompaniment of heat radiation, which we of course celebrate in winter, and which is significantly less per lux for daylight compared to artificial light (by about a third), the superiority of sunlight becomes even clearer.
This means that lighting via skylights is superior to a normal artificial lighting, simply because of the visual performance it renders.
“Lighting technology” to date has concerned itself overly with recognising viewed objects, and with humans’ well-being when subject to artificial lighting.
It is now clear that, in doing so, people's need for light has not been properly assessed. The use of sunlight and daylight must therefore now be taken into greater consideration, due to its life-enhancing and health-promoting effects.