Professor Russell Foster had the audience in the palm of his hand at the final session in the lightspace arena at last week’s LuxLive.
We all had an idea that if we really wanted to understand the science behind human-centric lighting then Foster, who led the pioneering team at Oxford University which discovered the eye’s third photosensitive cells, would be the man to help us do it and he didn’t disappoint.
Opening with the basics of how we see what we see, he soon headed off into the new landscape that we’re all struggling to find our way across – that of the non-visual receptor or the intrinsically photosensitive Retinal Ganglion Receptor (ipRGC). The is responsible for melatonin release from the pineal gland, or the ‘sleep hormone’ as it has become conveniently known.
In undertaking his research Foster and his team at Oxford were following up on a discovery back in 1923 that the pupils of blind mice still responded to the presence of light.
The idea that, if the rods and cones weren’t doing the work, something else must be, led the team to the discovery of the ipRGC which, in turn, led to the linkage between light and the effect that it has on our body clock – what we now all know as the circadian rhythm. Further study went on to identify the light conditions that are necessary to trigger the ‘melanopic response’ within the pineal gland.
On the back of this research the lighting industry has come to two conclusions:
That if we can control the melanopic response then we can control human behaviour.
That if we can establish a programme of ‘light dosage’ then we can create an internal visual environment that will work to the benefit of its occupants.
The final part of Foster’s programme threw a mighty shadow over any such assumptions and threw a hugely inconvenient spanner into any energy planning strategy that might rely on reduced lighting provision.
Burst bubble No.1:
While acknowledging that further research is necessary, so no one really knows what’s going on yet, the suspicion is that melatonin isn’t a ‘sleep hormone’ after all but is more likely to turn out to be an indicator that the body is getting itself ready for a period of sleep. Melatonin does not send us to sleep, so its suppression via blue-enriched light is unlikely to keep us alert.
Burst bubble No.2:
By extension, if the control of melatonin has no real impact on alertness, then there’s little point in promoting the idea of programmed lighting based simply on the blue content of the light source. Changing the colour of white light may be having an effect on behaviour, but it's more likely to be psychological of learned behaviour rather than a physiological response.
So far, so depressing for the human-centric lighting community. But what came next might cheer up the luminaire manufacturers. It turns out that the thing that we must ensure is that our circadian rhythm is properly synchronised with our natural environment. The best way to do this is to spend half an hour or so in a brightly-lit environment.
The obvious solution is to spend that time outside in the fresh air, sitting on a park bench, walking or cycling to work or sitting next to a window with a decent view. There are any number of ways of improving our lives that cost next to nothing.
On the other hand Foster suggested that our working space could be provided with additional illumination somewhere in the region of +1000Lux for that same amount of time. Sufficient research has been done to indicate that our circadian rhythms are best reinforced in this manner – the question remains, however . . . how do we do it?
Human-centric lighting companies have been looking for ways to put clear space between their systems and ‘conventional’ lighting products, though it’s doubtful that they ever imagined that increasing the lighting load – and therefore increasing the capital lighting cost – would be the preferred solution.
It probably won’t come to this; offices will not have a nuclear option of ramping up illuminance levels at the beginning of the day, but we can see the potential for the return of the ‘sensory space’ – that special room where we can go to listen to whale song, smell the aromatherapy oils and bask in artificial sunlight. I for one would be happy to queue for that one.