Re-designing artificial lights to suit our biological needs
Submitting InstitutionUniversity of Manchester
Unit of AssessmentBiological Sciences
Summary Impact TypeTechnological
Research Subject Area(s)
Biological Sciences: Physiology
Medical and Health Sciences: Neurosciences
Summary of the impact
Regulation of our sleep-wake cycle is crucial to health and well-being.
The quality (intensity and
spectral distribution) of artificial light is currently described
according to its ability to activate rod
and cone photoreceptors in the human eye. This approach ignores the
discovery of a third
photoreceptor that Lucas and his group have shown to be responsible for a
range of sub-conscious
neurophysiological and neurobehavioural responses to light, which together
strongly contribute to
health, productivity and well-being. Their research has established ways
of measuring light that
predict its effect on these newly discovered photoreceptors. They have
partnered with industrial
[text removed for publication] and public policy (various) organisations
to translate this knowledge
into improved artificial light sources and updated international standards
for architectural lighting,
for use in a wide range of domestic, public and industrial settings.
The impact is based upon research that took place in Manchester from 2003
to the present. Key
researchers in that time:
Professor Robert Lucas (2003-2004 Senior Lecturer; 2004-present GSK Chair
Post-doctoral research associates:
Dr Emma Tarttelin (2003-2009); Dr James Bellingham (2003-2007); Dr
Gurprit Lall (2004-2007); Dr
Vikki Revell (2007-2009); Dr Timothy Brown (2008-2012).
Jazi Al Enezi (2007-2010); Annette Allen (2008-2011).
The mammalian retina responds to light not only using the well-known rod
photoreceptors, but also through a third type of directly photoresponsive
cell. This additional
photoreceptor was discovered only ten years ago and comprises a particular
class of retinal
ganglion cell (termed intrinsically photosensitive retinal ganglion cells
or ipRGCs). Lucas's previous
work contributed to their discovery, and since 2003 his research group in
Manchester has been
studying the basic biology and functional significance of these ipRGC
1.) ipRGCs rely upon a protein called melanopsin for their sensitivity
2.) ipRGCs are the origin of a wide range of normal neurophysiological
responses to light , such as photoentrainment (synchronising the body's
rhythms to the light-dark cycle) and the pupillary light reflex (change in
pupil diameter with
light intensity), and also contribute to aspects of visual perception 
Given the importance of ipRGCs to normal human physiology and behaviour,
one area of particular
interest is how the discovery of this new photoreceptor can influence good
practice in the lighting
industry. At present, the intensity and spectral composition of artificial
lighting is determined solely
according to its impact upon cone and (to a lesser extent) rod
photoreceptors. There is now great
commercial and public policy interest in whether/how lighting could be
changed to ensure
adequate stimulation of the ipRGC photoreceptor.
In addressing this question, Lucas's group firstly determined the extent
to which the vital biological
systems that are responsive to rod/cone photoreceptors are also influenced
by ipRGCs, and thus
how important regulation of ipRGC activity is likely to be. In a series of
publications [4,5] they
demonstrated that ipRGCs provide information about the light environment
(absolute light intensity
under daylight conditions) that is not available from rods and cones and
that is an important
determinant of neurophysiological/neurobehavioural state. Secondly they
addressed how the
development of artificial lights could change to match the requirements of
ipRGCs. They have
shown that this is partly a matter of increasing light intensity [4,5].
However, ipRGCs are not
equally responsive to all wavelengths of light and so such increases
should be targeted at specific
parts of the spectrum. They have therefore conducted a number of
experiments describing the
spectral sensitivity of ipRGCs, which have culminated in the validation of
a robust and accessible
method for predicting the ipRGC activating efficiency of any polychromatic
References to the research
The research was published in the most prestigious interdisciplinary
journals and the best
respected journals in the fields of neuroscience and chronobiology.
1. Melyan Z, Tarttelin EE, Bellingham J, Lucas RJ, Hankins MW
(2005). Addition of human
melanopsin renders mammalian cells photoresponsive. Nature 433:741-5.
2. Güler AD, Ecker JL, Lall GS, Haq S, Altimus CM, Liao H-W,
Barnard AR, Cahill H, Badea
TC, Zhao H, Hankins MW, Berson DM, Lucas RJ, Yau K-W and Hattar S.
Melanopsin cells are the principal conduits for rod-cone input to
Nature 453:102-105. doi: 10.1038/nature06829
3. Brown TM, Gias C, Hatori M, Keding SR,
Semo M, Coffey PJ, Gigg J, Piggins
HD, Panda S,
Lucas RJ (2010) Melanopsin Contributions to Irradiance Coding in
Visual System. PLoS Biology 8(12):e1000558.
4. Lall GS, Revell VL, Momiji M, al Enezi J,
Altimus CM, Güler AD, Aguilar C, Cameron MA,
Allender A, Hankins MW, Hattar S and Lucas RJ
(2010). Distinct contributions of rod, cone
and melanopsin photoreceptors to encoding irradiance. Neuron 66:417-28.
5. Brown TM, Wynne J, Piggins HD, Lucas RJ
(2011). Multiple hypothalamic cell populations
encoding distinct visual information. J Physiol 589(5)1173-94.
6. al Enezi J, Revell V, Brown TM, Wynne J, Schlangen L, Lucas
R (2011). A `melanopic'
spectral efficiency function predicts the sensitivity of melanopsin
polychromatic lights. J Biol Rhythms 26(4):314-23.
Details of the impact
It is now widely accepted that disruption of the circadian clock and
sleep-wake cycle due to
unnatural light exposure can have a profound influence on human health and
well-being. This is
particularly relevant in shift-workers and care home residents, who
experience sleep disturbance
due to a lack of natural daylight, and frequent long-haul travellers
(jet-lag). Lucas's research has
shown that ipRGCs play a distinct role in synchronising endogenous
circadian clocks to the
external light-dark cycle, and his group has developed a robust novel
method for measuring light
that activates these photoreceptors. Therefore these findings have
important implications for the
development of improved artificial light sources and updated standards for
Pathways to impact
An important component of Lucas's strategy to maximise impact has been to
publicise his group's
research to the lighting industry. They have achieved this by publishing
review articles in industry-
focussed publications (e.g. CIE proceedings, Commission Internationale de
International Commission on Illumination, the international
standardisation body for light and
lighting, colour and vision, photobiology and image technology), and
presenting their work at
conferences for industrial researchers organised by the UK National
Physical Laboratory, the
Deutsches Institut fur Normung (the German institute for standardisation),
the Society for Light
Treatment and Biological Rhythms, and the International Symposium on the
Technology of Lighting. These activities led to three more formal
interactions with beneficiaries of
1.) [text removed for publication].
2.) Since 2011, Lucas has acted as UK representative on a committee
169; Working Group 13) established by the European Committee for
to define new units of measurement for light that are relevant for ipRGCs
[B]. Defining how
to measure light is a first step for validating new products and
ultimately for bringing in new
standards for artificial light environments and light pollution.
Currently, there is no accepted
way of predicting how effective a given light source will be at activating
photoreceptors. Lucas's findings (especially ) provide the basis for
addressing this deficit,
and have defined the working draft of this committee's report [C].
3.) In January 2013 Lucas organised and chaired an international
conference in Manchester,
sponsored by the German Electrical and Electronic Manufacturers`
Association, to bring
together researchers to agree guidelines on light measurement — based upon
knowledge of ipRGCs — that can be used by industry and regulatory bodies.
of the meeting will be published as a report on best practice in light
was commissioned by Div 6 of the CIE on 28 February 2013. It is scheduled
published as a stand-alone report on the CIE website
in the first quarter of 2014 [D].
Reach and significance of the impact:
Commercial applications and product development:
A large number of manufacturers worldwide now market blue-enhanced high
sources for therapeutic applications and/or to replace standard lumieres
domestic/public/industrial settings. Lucas's descriptions of melanopsin's
spectral sensitivity (i.e. to
blue light)  and the significance of ipRGCs for setting
(e.g. [2,4,5]) provide much of the scientific justification for this
approach. [text removed for publication].
There is growing interest in how standards and recommendations for
artificial lighting should be
modified to take account of ipRGCs. Lucas has directly influenced policy
in this area by
contributing advice based upon his research (especially [1,2]) to the
Royal Commission on
Environmental Pollution's 2009 report on `Artificial Light in the
Environment', in which he is named
as a contributor [E].
The most important barrier to developing national and international
guidelines on optimal levels of
ipRGC activation in architectural lighting is the absence of an
internationally accepted method of
measuring light intensity that is relevant for this new photoreceptor.
Lucas's research proposes just
such a metric . This research is referenced in the draft
recommendations of the CEN committee
169, working group 13 [B, C], and will be in the CIE report from the
January 2013 meeting Lucas
organised and chaired [D]. These guidelines will be used by industry and
worldwide to drive better alignment of artificial and architectural
lighting to our biological needs.
[text removed for publication].
Sources to corroborate the impact
A. [text removed for publication]
B. Letter of support from the Chair of CEN (European Committee for
Committee 169, Working Group 13, describing Lucas's influence in updating
standards of light measurement.
C. Draft report for the CEN TC 169/WG 13.
D. Letter of support from the Director of CIE Division 6 "Photochemistry
(Commission Internationale de L'Eclairage = International Commission on
describing Lucas's influence in updating international standards for light
E. Royal Commission on Environmental Pollution's 2009 report on
`Artificial Light in the