In the October issue of LEDs Magazine,
Deborah Burnett shared her opinions on
blue-rich LED light in “First do no harm”
( http://bit.ly/1l9Xc2d). Burnett brought
up some valid points, including that there
is a strong interaction with various medications and light, and that people need to
be careful about that. I believe, however,
that there are many benefits of cooler-CCT
lighting, and not leveraging those benefits
could do harm.
Since Burnett used the HCL (
human-centric lighting) term and it’s an area of great
interest, I felt obligated to write this column.
Although I am the vice-chair of the Human
Centric Lighting Society (HCLS), I wrote this
as an individual. Still, the HCLS has some of
the best neuroscientists and other experts
around the world. Following are my opinions based on what I have learned over the
last four years from people inside and out
of the HCLS.
It is true that not everything is known
about optimal light dosing for the non-visual part of the human physiological system.
Dosing is the amount, spectrum, time of day,
and duration of light. But enough is known to
significantly improve a lot of existing lighting. Keeping the existing lighting can often
cause harm. A common example is office
workers exposed to fluorescent or LED light
at 3000K or 3500K all day long. Such workers do not get very much daylight, and they
do not take sufficient breaks outside during
the day. Even fixed 5000K LED lighting would
be much better for both short- and long-term
alertness. Such light should not be used one
to two hours before going to bed.
Also, blue-enriched light can be better
than caffeine. I believe whether morning lark
or night owl, people have an innate sense of
the best light dosing at different times of the
day for different tasks without knowing any
of the neuroscience. Now we finally
have cost-effective tunable (
dimming and Kelvin or color changing) LED lights that individuals
can adjust as they want. Hopefully
somebody can get funding to scientifically research this.
There are some American lighting professionals who think that
incandescent light is the holy grail and who
do not like any high-CCT source. Some point
to the Kruithof Effect, even if good science has
shown it is not valid and the IES has stopped
referring to it.
Some existing top-down research, bot-tom-up research, and case studies on blue
light exist. We need all of them. My focus
is case studies, and my goal is to get many
HCL projects installed in the United States,
excluding applications with certain medications and other critical factors. We need
comprehensive evaluations that will help
the users and improve upcoming products
and future lighting design.
I recently completed an
HCL project in an elementary
school classroom with tun-
able 2700–6500K troffers and
fixed 10,000K troffers. Despite
the fact that some profession-
als think that people do not
like high CCTs, the teacher
and students typically have
the main troffers on at 6500K all day long.
And if the teacher forgets to also turn on the
10,000K troffers in the morning for math, the
students remind her and state they can learn
better with those lights also on.
Some people blame certain
types of interior and exterior
electric light for cancer and other
problems of third-shift workers
and others. The problem seems
to be being up during the night,
Steven Lockley, Rod Heller, and the Midwest Lighting Institute are doing a project,
which includes blue-enriched light, at a hospital to reduce those errors.
If you are not already aware, Europe is
way ahead of the United States regarding
HCL, and that seems to be based on good
science ( http://bit.ly/1gOTF6L).
Okay, readers, you are aware of two opinions. Now you should get information direct
from real experts, such as top-tier PhDs in
neuroscience, specialized MDs, and others.
A great start is the non-profit HCLS library
Keeping the existing lighting
can do harm
We may not fully understand the impact of blue-rich light on humans, states
STAN WALERCZYK, principal of Lighting Wizards, but we know it can be beneficial and
ignoring that benefit could be the act that does harm.
Research assesses the value of human-centric lighting
Potential exists for SSL to positively impact health and
wellbeing, but science lags
Questions abound about whether a blue-light hazard exists