Feature, Healthcare

‘Too early to start human-centric lighting’ – top scientist

Neuroscientist Russell Foster led the team at Oxford which discovered the eye’s third photosensitive cells in 1991

IT’S TOO EARLY to implement human-centric lighting, the world authority on the subject has declared.

Speaking at the lighting industry’s global gathering at the Light + Building 2018 exhibition in Frankfurt, Dr Russell Foster of Oxford University said: ‘We can’t develop human-centric lighting until we know what impact light has upon human biology across the day and night cycle’.

There is currently no standard lighting recipe that manufacturers can currently put into effect. He bluntly told his audience: ‘We simply don’t know’.

Dr Russell Foster was awarded the Lux Person of the Year in 2016 for his ground-breaking work on the eye and its relationship with light

There were many variables and unknowns in circadian light exposure which currently couldn’t be squared in a one-size-fits-all lighting system. For instance, people are different ‘chronotypes’ – whether they are ‘larks’ or ‘owls’ – and lighting effects each group differently.

He also clarified some of the scientific learnings of recent years.

For instance, while standard office lighting levels of 300 to 500 lux was enough to stimulate the visual system ‘but not the circadian one’, it could do so over a long duration, such as six and a half hours. He acknowledged that the academic community had given ‘mixed messages’ to the industry about this exposure profile in the past.

Foster’s blunt message won’t be universally welcomed in the industry, which is keen to commercialise the concept. Many lighting manufacturers have invested in the area and were already exhibiting so-called ‘human-centric lighting systems’ at the Frankfurt event.

Neuroscientist Russell Foster led the pioneering team at Oxford University which discovered the eye’s third photosensitive cells in 1991.

These are called intrinsically photosensitive retinal ganglion cells and are sensitive to a narrow range of blue light, around 480nm, and it’s these that are key to controlling our circadian rhythms with light.

When the amount of 480nm blue drops below a certain level, the pineal gland is instructed to secrete a hormone called melatonin, and it’s this biochemical messenger that effectively sets in train the body’s sleep pattern.

The discovery has changed our understanding and appreciation of the power of light to affect us. In fact, some are starting to describe light as a drug, such is its power to control our health and welling as well as our circadian rhythms.

The lighting industry, unsurprisingly, has jumped on the discovery as it opens up exciting new possibilities to create lighting systems that work more in harmony with people. 

It creates a whole new market of ‘circadian lighting’ at a time when lighting products are becoming commoditised. Early systems, already installed in some schools, workplaces and care homes, feature lighting whose intensity and colour temperature change during the day, allegedly to provide benefits to occupants.





  • Human-centric lighting will be explored in the Workplace and Wellbeing Conference at LuxLive 2018, Europe’s largest annual lighting event taking place on 14th & 15th November at the ExCeL London. Featuring eight conference tracks and over 100 expert industry speakers. Entry is FREE – simply register to attend HERE