Scientists Identify Exact Light to Trigger Sleep-Wake Cycle – July 2020 Newsletter

This article featured in Lux Review’s publication, you can find the original article here –

A paper, published in the Journal of Biological Rhythms on 18 June 2020 today, revealed that 477 nanometres is the most potent light to control people’s circadian rhythm.

Scientists say they have identified the exact wavelength of light which controls the sleep-wake cycle of humans. A paper, published in the Journal of Biological Rhythms today, revealed that 477 nanometres is the most potent light to control people’s circadian rhythm. The researchers have dubbed it ‘Circadian Blue’.

The study has major implications for how artificial lighting will be engineered to optimise human health. Blue light exposure at night is a well-established public health hazard. It suppresses melatonin, the body’s sleep-wake hormone, and causes circadian disruption, and is linked to an increased risk of sleep disorders, obesity, diabetes, and breast and prostate cancer.

‘Our goal was to define the exact wavelengths of light that triggers the human circadian system in real-world lighting conditions’ said Dr. Martin Moore-Ede, a former professor at Harvard Medical School and CEO at Circadian ZircLight. ‘We found the critical blue light signal falls between 438-493nm with a peak at 477nm. This is the missing key to managing the health risks of light at night.’

The Circadian Light Research Center team used an interesting feature of white light to tease out the circadian-sensitive wavelengths: white lights can be built from a wide variety of colour spectral combinations.

They recruited 34 male and female study subjects, who were exposed on each test night to a different LED or fluorescent white light spectra for 12 hours. Throughout each night, melatonin levels were measured.

‘We found melatonin suppression levels varied widely depending on the light source’s unique spectral characteristics,’ said Dr. Anneke Heitman, a study co-author. ‘This data enabled us to isolate the impact of individual wavelengths of light and determine the colour of Circadian Blue.
‘Previous research into the spectral sensitivity of the circadian clock was done in dark-adapted conditions with short exposures to monochromatic lights. ‘However, at home and at work, we spend the vast majority of our time in a light-adapted state, exposed to white polychromatic light,’ said Dr. Moore-Ede. ‘Our study reflects how we interact with light in the real-world.’

Based on these findings, the company Circadian ZircLight built and patented spectrally-engineered LEDs that synchronise circadian rhythms during the day and prevent circadian disruption at night by controlling the Circadian Blue dosage. The firm said this work led to the first UL verified LED to emit less than 2 per cent blue light at night. In addition to building their own fixtures, Circadian ZircLight has licensed the LED technology to other lighting companies, including Acuity Brands, to meet the growing demand for circadian lighting.


I am really excited about the remainder of this year.  The time for dwelling on COVID-19 News is past.  Continuously thinking about and discussing that subject will simply pull one down and distract one from the real objectives.

I have started the process of revising every Module of the Advanced Diploma in Illumination Engineering course.  The aim is to ensure that the content is always up to date, is accurate and academically correct.  I also ensure that it reflects the doctrine of CIE, of all the standards authorities and institutions around the world.

Our webinars continue to attract attendees from around the world.  If you have not attended the webinars, you are doing yourself a disservice. More recently, we have been privileged to secure the services of overseas professional illumination engineers to deliver presentations for our forthcoming webinars.

I attend a weekly meeting with the members of The Institution of Lighting Professionals (UK) every Monday from 16;00 to 18:00 SA time.  I have not only met some wonderful people, each of them professionals and ready to share with the members.  I have benefited significantly.  I have learnt so much and enjoyed networking.

Some students have already benefited from private lessons which dealt with subjects or parts thereof that they struggled with.  Remember that if you experience any difficulties, there are two options available to you.

a.  You can enjoy personal mentoring session which is a short call, or;
b.  You can request a private lesson which is an online tutoring session using Microsoft Teams for 1 hour for a small fee.  I work with the students during the lesson to ensure that before the end of the lesson, they have an excellent understanding and have overcome their problem.

The script for the first video lesson has been completed and the video will be produced soon and be added to our system.  Each lesson will deal with one aspect that I have identified in a module that a number of students have found to be more challenging.

An exciting new addition to the overall e-learning experience will be group assignments.  At a point in the course where students have acquired a suitable level of knowledge, student groups will be identified.  The group will meet online on Microsoft Teams.  Once they have been briefed about the assignment to be completed, they will be assigned to breakaway rooms in pairs.  Each pair of students will work together to solve the assignment and prepare a presentation to show their solution.  The students will return to the online classroom.  Each pair of students will present their solution.  In this way, the entire group will benefit.  At the same time, they will be taught the best methods to present similar solutions so that they will be best prepared for the real world in business.

We are continuously working to further improve our excellent e-learning course content and the student’s overall learning experience.

Perfection takes time and hard work to achieve!

It’s time to welcome new students:

        • Nicole Farman, Architect, Chicago Illinois, USA – BHASL003C19: Advanced Diploma in Illumination Engineering
        • Mark Storm, Property Developer, Cape Town – BHASL003C19: Advanced Diploma in Illumination Engineering
        • Rhydian Smith, Lighting Revolution, Cape Town – BHASL003C19: Advanced Diploma in Illumination Engineering
        • George DF Piek, Giant Light, Johannesburg – BHASL018: Online Relux High Level Course

Happy birthday to each of you. Have a fantastic day!

                • Renske Snyman, Cape Town – 1 July
                • Hardus Pieterse, Centurion – 2 July
                • Tammy de Oliveira, Cape Town – 4 July
                • Hendrik Chandler, Mosselbay – 5 July
                • Jean-Paul Muambayi, Cape Town – 6 July
                • Mkhanyisi Zulu, Mossel Bay – 8 July
                • Clive Townsley, Gaborone, Botswana – 16 July
                • Elizabeth Kahwenga, Centurion – 17 July
                • Sharron Burger, Durban – 18 July
                • Dalette Britz, Midrand – 20 July
                • Francois Joubert. Orania – 20 July
                • Daniel Hammond, Cape Town – 21 July
                • Travis Booth, New Zealand – 22 July
                • Leonel Esteban Garcia Nunez, Mexico City, Mexico – 23 July
                • Lynette Jeppe, Bloemfontein – 24 July
                • Beth Maina, Nairobi, Kenya – 27 July
                • Kubeshan Gopaul, Johannesburg – 28 July

Andre Roosenschoon, Culco, Architect, Durban
Graduated on 10 June 2020, Cum Laude

Well done! You were an exemplary student.  We wish you every success in the future!

EnLightened Community Meetings

Join us every Tuesday from 13:00 to 14:00 for an informal chat about any subject under the sun as long as it is positive.  Join us for moral support and networking.


2 July – “The intrigue of colour” – Presenter: Philip Hammond, BHA School of Lighting, Cape Town, South Africa
9 July – “Light Nutrition” – Presenter: Terry John, Life Light Studio, London, United Kingdom
16 July – “Reviewing the Situation”, a particular focus on the Post COVID 19 Era, even if it continues into 2022. Presenter: Philip Hammond, BHA School of Lighting, Cape Town, South Africa
23 July – “International changes to Street and Pathway Lighting” – Presenter: Nick Smith, Nick Smith Associates, Chesterfield, United Kingdom
30 July – TBA
NOTE:  In the event of load reduction by Eskom, the electricity utiliity, on any of the scheduled dates, alternative dates for the affected presentations will be notified to all registrants.

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Face Masks under Blue UV-C Light

In a statement published on 4 June 2020, the Global Lighting Association (GLA) says UV-C will be a useful tool in the fight against the Covid-19 pandemic’ but it is increasingly concerned at the proliferation of UV disinfecting devices with ‘dubious safety features and inadequate safety instructions’.

The Global Lighting Association has added its voice to debate on the use of ultraviolet light to tackle the coronavirus pandemic.

It says it is becoming increasingly concerned at the proliferation of disinfecting devices based on ultraviolet lighting – particularly being sold on the internet – with dubious safety features and inadequate safety instructions.

This week the association issued a position statement containing guidelines for the safe use of UV-C devices.

It said germicidal ultraviolet irradiation ‘is a proven methodology’ for inactivating viruses on solid surfaces, in water and in air.
‘As such it is expected to be a useful tool in the fight against the Covid-19 pandemic’.

UV-C is a category of ultraviolet light with wavelengths between 100-280 nanometres and is the most effective UV light for disinfection.
The GLA said: ‘While UV-C is helping to contain viruses, if not used properly it can pose risks to human health’.

GLA ‘is concerned at the proliferation of UV disinfecting devices with dubious safety features and inadequate safety instructions’.
Standardisation bodies are expected to develop comprehensive standards for the safe operation of UV-C devices.

However, the GLA cautioned that this process will take many months, if not years.

In the interests of public safety, as an interim measure the Global Lighting Association brought together industry experts and developed guidelines to assist users and manufacturers pending publication of these standards.

The GLA paper echoes advice from the Illuminating Engineering Society, which weighed into the debate about the coronavirus and ultraviolet lighting in April.

IES scientists confirmed that a particular section of ultraviolet light – shortwave ultraviolet light from 200 to 280 nanometres, termed UV-C – can kill the coronavirus at the right dose.

However, the IES cautioned against using UV-C lights to disinfect surfaces, and recommends that the lighting industry concentrate its efforts on disinfecting the air instead.

‘While UV-C could be a secondary infection control measure for disinfecting potential germ-carrying deposits on accessible (not-shadowed) surfaces, its great value would be in disinfecting air in areas where this may be a concern’.

Examples could include intensive care wards.

‘Upper-air germicidal ultraviolet is the safest, most effective application of UV-C.

‘In special locations, where viral transmission is highly likely, whole-room UV germicidal irradiation from suspended fixtures directing UV-C downward could be applied, provided strict precautions can be followed.

Interest in UV-C lighting has soared since the coronavirus outbreak. Earlier this month, 3,000 individuals from 59 countries watched a four-hour long IES webinar on the subject, making it the highest attended event in the history of the organisation.

If you would like a copy of The Global Lighting Association Position Statement on Germicidal UV-C Irradiation or The Institution of Lighting Professionals (UK) position on this issue, contact


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