BIODYNAMIC LIGHTING Lighting
that adapts to influence the
body – changing in brightness or
colour content depending on the
application, activity or time of day.
CHRONOBIOLOG Y The study
of time cycles in living things –
particularly how we are influenced
by solar and lunar cycles.
CIRCADIAN RHYTHM The body’s
natural daily rhythm.
CC T The correlated colour
temperature of light – how ‘warm’
or ‘cool’ it appears. Visually, this is
one way we can tell what time
of day it is, because natural light
is cooler at midday and warmer
in the morning and evening.
However, it’s not the colour
temperature itself that influences
our bodily rhythms – it’s a particular
wavelength of blue contained in
the light. An LED and a fluorescent
lamp that appear to be the same
colour temperature as each other
will actually contain different
amounts of blue and have different
effects on our bodies.
460NM BLUE The approximate
wavelength (in nanometres) of
blue light that cells in the eye
detect, triggering the release
of hormones that make us feel
awake and influencing our
MELATONIN The hormone that
regulates our sleep-wake cycle. It is
suppressed by blue light, so that we
feel awake during the day.
RETINAL GANGLION CELLS Cells
in the retina that detect light. Most
of them help us see, but recently it
has been discovered that some of
them also look out for blue light,
using it to determine what time
of day it is and regulate our body
SPECTRAL COMPOSITION The
range of colours in a light source.
Because white light is composed
of different combinations of
colours, two light sources that
look the same may contain a lot
or a little of the particular type
of blue that affects our bodies.
Most white LEDs are actually blue
with a yellow phosphor, so they
tend to have a high blue spectral
composition even if they don’t
BIODYNAMIC CHEAT SHEET
Professor Paulo Di Trapani basks
beneath the LED-based artificial
skylight he spent 10 years
developing. LEDs are opening
up exciting new possibilities in