The human body is controlled by the biological clock – which is in its
turn controlled by light. Lighting and light setting are important for us,
since we spend on average 90% of our waking hours indoors.
Light has an enormous effect on us human beings. On our vision, of course, but also on our mood and our activity level. The human daily rhythm is adapted to the sun. We are more alert and perform better during the day, and recuperate at night.
Light bulb, fluorescent strip light or led?
Our reaction to light is connected with the light intensity and colour temperature. Therefore the characteristics and quality of the artificial light around us are of great importance. A light bulb has the whole spectrum of light waves, just like daylight, but is an energy-inefficient source of light. A fluorescent strip light does not have the same spectrum, and therefore does not have the same effect on our need for light. Certain light sources are sensitive to alternating current, which creates a subliminal flicker which can cause headaches and create the sensation of stress.
The new led lights are a good alternative, since they are energy-efficient, have very good colour reproduction and a low amount of subliminal flicker. It is important to be careful when choosing led lights, since the quality can vary enormously.
Human centric lighting – biologically effective light
Lighting also has non-visual effects. Human centric lighting is so-called dynamic light, which means that you can vary both lighting strength and light colour during the day, which can support the human daily rhythm, increase concentration, prevent sleep problems and improve our general well-being. Such solutions in schools, offices and hospitals can give students, staff and patients increased energy and motivation. In countries with little daylight during the winter months, an adjustable light temperature can reduce winter depression and other season-related illnesses.
Thorbjörn Laike's good advice for a good light environment in the workplace.
Daylight is the best source
Windows are the absolute best light source you can have. There is no other light that can replace daylight completely.
Lots of light, but not glaring
Best of all is indirect light which is directed via the walls and ceiling. A glaring lamp can have a directly negative effect on the body, since we fend off light, which in turn leads to an incorrect working position.
Mix light sources
Fluorescent tube lights give good general light. Combine them with the new type of narrow-beam diode lights which you can use for sculpting light and shadows in the room.
Good light fittings have reflectors to counteract dazzling. So as not to generate glare and reflections on screens, they should be hung from the ceiling to provide indirect light, just behind the actual workplace.
Supplement with individual light
People have different lighting needs. It is important to be able to control your personal lighting needs. A desk lamp may be the solution.
Age affects us
Light is immensely important for young people, since poor light can cause short-sightedness. At the age of 40+, the need for light becomes greater and greater, and an increased amount of light is a common need.
TORBJÖRN LAIKE is senior lecturer and adjunct professor in environmental psychology
and PhD in psychology at Lund University. He researches how people are affected by light
in indoor environments, and how artificial light can affect us. In particular, his research
has focused on the non-visual effects of light and colour, i.e. how these environmental
characteristics influence our well-being and how we feel. Our well-being is important
both for our behaviour and for our performance. Torbjörn is also head of CEEBEL,
a national education centre for energy-efficient lighting, whose purpose is to coordinate,
disseminate and initiate research into light and lighting in Sweden.
* A flicker which we do not perceive with
the eye, about 100 times per second)
** Light Emitting Diodes