Technical information

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Light planning
Light and health
Light, or light radiation, not only aects our visual cortex but
also the whole of our alertness, wellbeing and performance. Our
circadian rhythm and seasonal variation are genetically fixed, but
they are regulated to a certain extent by our surroundings, above all
by light. Nerve pathways from the eye's retina signal to cells in the
brain to stop secreting the hormone melatonin, which is believed to
control our circadian rhythm. Interruptions to the circadian rhythm,
due to a lack of daylight during the winter months, is considered to
be the primary cause of seasonal aective disorder (SAD).
The eect of light on humans
New research has shown that light also aects a new third receptor
as well as both the rods and cones. A discovery which has been iden-
tied as the missing link between how our health and wellbeing are
connected to light.
This receptor aects dierent hormones in the brain such as the
secretion of the sleep hormone melatonin, which is produced at
lower light levels or in the dark. Conversely, at higher light levels, the
stress hormone cortisol is produced. For 150 years, we have focused
on the visual eects of light, but with the discovery of the new re-
ceptors we must also in future take into account the biological and
emotional eects of light on man.
Increased demands on lighting planning
In order to gain a greater understanding of how light in our sur-
roundings eects our wellbeing Fagerhult’s Lighting Technology
Manager Tommy Govén, in conjunction with Professor Thorbjörn
Laike from the Department of Architecture and Built Environment
at Lund University, have conducted an application study on the
subject.
The study shows that the body is influenced to a great extent by
normal ambient light at ± 30˚ in the horizontal line of vision. The
most positive eects with regards to human alertness, wellbeing
and performance are observed at approx. 100 cd/m² on walls with a
horizontal illuminance of 500 lx.
100 cd/m² seems to be an optimal level for vertical ambient light
– something which poses questions about current lighting levels in
The study clearly shows that the body is influenced to a great extent by normal
ambient light at ± 30˚ in the horizontal line of vision. The most positive eects with
regards to human alertness, wellbeing and performance are observed at approx. 100
cd/m² on walls with a horizontal illuminance of 500 lx.
L
av
1 = 20 cd/m²
L
av
2 = 100 cd/m²
L
av
3 = 350 cd/m²
E
h
= 500 lx
constant value
Perceived values
Visual
In the future, lighting planning will be more focused on visual, biological and
emotional aspects.
oces, which is usually three to four times lower (20–30 cd/m²).
The study also showed that ambient light influences the stress
hormones in the body and alertness in a relatively short time. It is
therefore possible, by using algorithmic lighting controls, to change
our biological clock over time. For example, in the morning during
the dark months of the year, increase activity with more ambient
light.
How is lighting planning aected?
The discovery that certain elements of light radiation also aect our
wellbeing will influence the future design and evaluation of lighting
in our rooms.
This may lead to a greater focus on the lighting of our surround-
ings but also on varying light and its colour over time. This will be
especially important in rooms that do not have a supply of natural
daylight. Within healthcare, light has long been used for the medi-
cal treatment of skin conditions and in order to reduce the eects
of SAD (seasonal aective disorder). In the future, lighting planning
will be more focused on visual, biological and emotional aspects.
Biological
Emotional
Methodology of the test
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