In today’s society people spend most of their time inside buildings, on average more than
90 %. In confined spaces there is often not much natural light available and artificial
lighting remains on for many hours, so we can lose contact with the dynamic pattern of
daylight due to the constant level of artificial lighting. What are the consequences for the
body? Lack of daylight during the day tends to change the functioning of the internal clock
and alter the phases of sleep and wakefulness to a greater or lesser extent with a negative
effect on chronobiological rhythms and, in extreme cases, cause health problems.
Human Centric Lighting (HCL)
THE NEW DESIGN PARADIGM
The effect of lighting on humans
For a long time, the main objective of lighting was to satisfy the visual needs of human
beings: in environments with insufficient natural light, simple and obvious actions such
as seeing and being seen, identifying obstacles, reading or distinguishing colours are
possible thanks to artificial lighting. In recent years there has been a focus on the need
to reduce energy consumption in buildings and the resulting emissions of pollutant and
climate-altering gases. For this reason, the revolution caused by the advent of LED sources
has been appreciated above all from the point of view of the gain in energy efficiency; less
attention has been paid to the great potential for control and new applications that this
technology offers. At the same time, it became clear that light also has other relevant
effects on human beings besides the purely visual one: biological effects and emotional
effects. It is common experience that light is not neutral when considering aspects of
everyday life such as mood or the waking and sleeping cycle. But a decisive step in
demonstrating that circadian rhythms are correlated with light conditions was taken in
2001, with the scientific discovery of the presence of a third photoreceptor in the human
eye alongside those already known: rods and cones.
Light and the internal clock
Over hundreds of thousands of years, the body has adapted to the alternation of day and
night. In humans, it is natural light that synchronises the internal clock, which plays a key
role in controlling not only the daily waking and sleeping phases, but also the heart rate,
blood pressure and mood. To this end, the body naturally produces hormones such as
cortisol and melatonin, which are counter-cyclical. Early in the morning, the production
of cortisol - also known as the ‘stress hormone’ - begins, which has a stimulating effect
on many functions in the body and promotes awakening, activation and concentration.
Without an increase in cortisol levels, it would be difficult to get up in the morning and
much more difficult to carry out daily activities. After peaking around 9 a.m., its level
in the blood steadily decreases throughout the day. Melatonin production, on the other
hand, begins in the late afternoon. Known as the ‘sleep hormone’, it slows down the body’s
functions and lowers activity levels to facilitate sleep. Melatonin levels are already high
at midnight and reach their peak around 3am; the first light of day stops their production.
Visual
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HCL
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SMART LIGHTING
SMART LIGHTING
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