ISO/CIE TR 21783:2022

TECHNICAL ISO/CIE TR
REPORT 21783
First edition
2022-09
Light and lighting — Integrative
lighting — Non-visual effects
Lumière et éclairage — Éclairage intégratif — Effets non visuels
Reference number
ISO/CIE TR 21783:2022(E)
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ISO/CIE TR 21783:2022(E)
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Published in Switzerland
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ISO/CIE TR 21783:2022(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Practical implementation. 2
4.1 General . 2
4.2 Beneficial aims. 3
4.2.1 General . 3
4.2.2 Well established . 3
4.2.3 Moderate evidence . 3
4.2.4 Insufficient evidence . . 4
4.3 Avoidance of risks . 4
4.3.1 General . 4
4.3.2 Well established . 4
4.3.3 Moderate evidence . . 4
4.3.4 Insufficient evidence . . 5
4.4 Implementation Considerations . 5
4.5 Conclusion . 5
Annex A (informative) Scientific background . 7
Bibliography .14
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ISO/CIE TR 21783:2022(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
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any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
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iso/foreword.html.
This document was prepared by ISO/TC 274, Light and lighting in cooperation with the International
Commission on Illumination (CIE).
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
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ISO/CIE TR 21783:2022(E)
Introduction
The content of this document represents the state of the art at the date of publication and it is not
necessarily complete.
At present ipRGC-influenced responses to light (IIL responses) are often referred to as non-image-
forming (NIF) or non-visual (NV) responses to reflect their distinction from perceptual vision. This
document reflects that interest while allowing for the possibility for the accepted range of light
responses driven by ipRGCs to expand as we gain more knowledge.
The light patterns of exposure can be beneficial or non-beneficial for humans depending on the setting,
relating to spectrum, intensity, duration, and timing of the resulting light exposure.
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TECHNICAL REPORT ISO/CIE TR 21783:2022(E)
Light and lighting — Integrative lighting — Non-visual
effects
1 Scope
This document provides an analysis and evaluation of the current state of the art with regard to
ipRGC-influenced responses to light in applying this knowledge in the context of identified topics to
be considered for use in lighting applications. This analysis has taken into consideration published
scientific papers, use cases, reports, best-practice guidelines and recommendations, see Annex A.
However, evaluation of the results will be based on scientifically validated findings.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
CIE S 017:2020, ILV: International Lighting Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in CIE S 017 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
CIE maintains a terminology database for use in standardization at the following address:
— e-ILV: available at https:// cie .co .at/ e -ilv
3.1
integrative lighting
lighting integrating both visual and non-visual effects, and producing physiological and/or psychological
benefits upon humans
Note 1 to entry: The term "integrative lighting" applies only to humans.
Note 2 to entry: Lighting primarily for therapeutic purposes (light therapy) is not included.
Note 3 to entry: The term "human centric lighting" is used with a similar meaning.
[SOURCE: CIE S 017:2020, entry 17-29-028]
3.2
ipRGCs
intrinsically-photosensitive retinal ganglion cells
retinal ganglion cells that are photosensitive by means of the photopigment melanopsin
[SOURCE: CIE S 026:2018, entry 3.11, modified — notes to entry omitted]
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3.3
ipRGC-influenced responses to light
ipRGC-influenced light (IIL) responses
light-induced responses or effects that can be elicited by ipRGCs
Note 1 to entry: ipRGCs can play a role in both visual and non-visual responses to ocular light exposure. At
present ipRGC-influenced responses to light are often referred to as non-image-forming (NIF) or non-visual (NV)
responses to reflect their distinction from perceptual vision.
Note 2 to entry: ipRGC-influenced responses to light can be influenced by rod, cone and melanopsin inputs.
[SOURCE: CIE S 026:2018, entry 3.12, modified — notes 1 and 2 to entry revised]
3.4
spectrum
display or specification of the monochromatic components of the radiation considered
[SOURCE: CIE S 017:2020, entry 17-21-015, modified — notes to entry omitted]
3.5
illuminance
density of incident luminous flux with respect to area at a point on a real or imaginary surface
dΦ
v
E =
v
dA
where
Φ is luminous flux;
v
A is the area on which the luminous flux is incident.
−2
Note 1 to entry: The illuminance is expressed in lux (lx = lm·m ).
[SOURCE: CIE S 017:2020, entry 17-21-060, modified — notes 1 and 2 to entry omitted]
3.6
electric lighting
lighting by electric light sources
[SOURCE: CIE S 017:2020, entry 17-29-025, modified — notes to entry omitted]
3.7
daylighting
lighting for which daylight is the light source
[SOURCE: CIE S 017:2020, entry 17-29-031, modified — notes to entry omitted]
4 Practical implementation
4.1 General
Daylighting and electric lighting can affect psychological and biological functioning via image-forming
[1]
and non-image-forming pathways. Due to benefits and risks that relate to both pathways, experience
has shown that both ought to be considered in the lighting design process. Knowledge about both
image-forming and non-image-forming effects of lighting enables a better evaluation of the effects of
daylighting and electric lighting on the human body.
In particular, the processing of information contained in the light beyond the forming of images plays
a crucial role. Among other things, this additional information can influence the human internal
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clock and circadian rhythm. Besides the quantitative properties of light in the space as defined in
[64]
CIE S 026:2018, their temporal course is also of central importance. In practice, this means that a
given lighting installation, which will always have non-image-forming effects (positive or negative), is
managed in a suitable way in order to make positive use of the lighting.
All lighting installations will have effects on visual and physiological systems and can be intentionally
designed for these effects. Best results will occur when the lighting designer works with a
multidisciplinary team that includes occupational health experts, psychologists and others.
4.2 Beneficial aims
4.2.1 General
Considerations with regard to beneficial effects of light on humans focus on criteria for daylighting and
electric lighting. These considerations can be identified in addition to the classic visual criteria as listed
[65]
in ISO 8995-1 and are not meant to affect the visibility and quality of vision. The considerations are
grouped based on the strength of the scientific evidence at the time of writing. Well-established effects
have a strong body of scientific literature to support them. Moderate evidence effects have a smaller
scientific literature basis, but the evidence is consistent across studies. Insufficient evidence effects are
emerging areas with less consistent effects and low consensus. This classification into levels of evidence
only represents the status as at the end of 2019. Future research and publications might provide new
insights resulting in a different level of evidence.
For the individual planning and implementation of integrative lighting, it is important to determine the
desired outcomes and to prioritize their importance. This requires an understanding of the conditions
to which users can be exposed over the entire day and night (e.g. during working hours, while at home
or in transition). The effects of any light exposure also depend on the state of the individual, including
their prior light history and their internal states (e.g. groups of individuals in an airport could have
differing states of jet lag or circadian disruption).
Therefore, an informed design choice taking into account at least the following considerations is
advisable:
— probability of achieving the desired outcome;
— net benefits of the desired outcome.
IMPORTANT — The beneficial results of integrative lighting can only be achieved if it is planned
and applied correctly by qualified specialists. Equally important is the correct operation of the
lighting system by the actors/users involved.
The scientific background to the conclusions below is presented in Annex A.
4.2.2 Well established
The following are well established:
Integrative lighting can synchronize and support the human circadian system. To achieve this goal, it
is necessary to establish a strong daily light-dark pattern when planning and implementing daylighting
and electric lighting.
Integrative lighting can be beneficial for both acute and long-term effects on well-being and mood
states.
4.2.3 Moderate evidence
There is moderate evidence for the following:
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Integrative lighting can have positive effects on sleep quality, sleep onset and performance on the
subsequent days. This is partly based on avoiding a possible negative influence on the circadian system
by the non-visual effects of the electric lighting.
Integrative lighting can activate, increase cognitive performance and reduce sleepiness during evening/
night-time, which might be desirable for night work. These influences can also be sought in the short
term, without taking into account a daily course.
[2,3]
Integrative lighting might benefit some individuals with medical conditions such as dementia .
4.2.4 Insufficient evidence
There is insufficient evidence for the following:
Integrative lighting can activate, increase cognitive performance and reduce sleepiness during daytime.
These influences can also be sought in the short term, without taking into account a daily course.
Integrative lighting could increase academic performance and concentration. There is some evidence
from animal models, but limited evidence in human populations and none published showing longer-
term benefits.
4.3 Avoidance of risks
4.3.1 General
As already mentioned, the consideration of benefits and risks is an important task in the planning and
commissioning of a lighting installation. In particular, risk prevention measures can be recommended
for some specific applications and lighting situations.
4.3.2 Well established
The following are well established:
Light exposures below established exposure limits published by the International Commission on Non-
Ionizing Radiation Protection (ICNIRP) will avoid any risk of injury to the visual system.
Exposure to light during night shifts can reduce melatonin secretion and affect the timing of sleep. This
is one possible contributing factor in the aetiology of some adverse health effects of night shift work.
If night-shift work cannot be avoided, lighting patterns need to be planned to take into account the
shift schedule, and users need to maintain 24-hour patterns of light and dark exposure to achieve the
intended results. Darkness during sleeping hours would be good practice. The negative health impacts
of most night-shift schedules cannot be fully mitigated by integrative lighting.
For many people insufficient levels of lighting during the daytime can have negative physiological
effects. Too much light at the wrong time for the wrong activity and person can be detrimental to well-
being. The challenge is to understand the user group and needs well in order to avoid mismatches.
4.3.3 Moderate evidence
There is moderate evidence for the following:
High light exposure in the evening hours can cause sleep disturbances.
Interactions between the circadian system and safety at work have to be taken into account (e.g. the
need to maintain alertness in night-shift medical staff throughout the shift and on the travel home).
Different light exposures might be needed for different age groups to account for changes in short-
wavelength transmission in the eye. Young children are more sensitive to short-wavelength optical
radiation than adults, because of higher transmission of the lens of the eye at these wavelengths.
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4.3.4 Insufficient evidence
There is insufficient evidence for the following:
If night-shift work cannot be avoided, filtering out short wavelengths during night work could maintain
alertness with less circadian disruption.
Very high intensity "blue enriched light" can compete with natural light as a zeitgeber. This can
counteract seasonal adaptation of the biological clock. Thus, dynamics of lighting aimed at biological
effects have to consider seasonal changes in natural light exposure.
4.4 Implementation Considerations
In planning an integrative lighting installation, it is important that the aims above be achieved in
concert with the established aims of a high-quality lighting installation, such as providing positive and
avoiding negative physiological effects, supporting visual tasks, providing good colour rendering and
spatial brightness. This requires a careful consideration of several factors, including:
— occupant profile (e.g. age distribution, visual conditions, state of health) of the expected users of the
space;
— activity profile: predominantly transitory, predominantly sedentary, predominantly active but at a
fixed position, etc.; and
— predominantly controlled (e.g. institutionalized) or predominantly uncontrolled population.
These factors can be reviewed to produce an assessment of:
— potential health conditions expected to be encountered;
— generalized expectations of sleep patterns (e.g. it can be reasonably expected that teenagers will
generally have different sleep routines compared to elderly occupants);
— the quantity of light required at the eye to achieve a defined circadian stimulation, which will differ
between individuals.
NOTE These lists are not exhaustive.
Achieving the aims will not depend on light sources and lighting installations alone, but requires
consideration of control systems, training on their appropriate use, and user understanding and
acceptance. Considerations include:
— Interindividual differences (e.g. chronotypes, sensitivity to light) cannot fully be considered in a
fixed design, but could be managed using controls and local modifications.
— Conflicts of priorities between different needs (of the same or different users in one space) can
occur. This has to be solved by the designer in a way that does not compromise lighting quality.
— Problems can occur when individuals have control over the lighting but inadequate instructions on
how to use it in a beneficial way. Provision of detailed and easy to understand instructions is likely
to mitigate this problem.
— The power of building operators (such as employers) to decide on the time and duration of activation
can result in problems of acceptance of lighting. This needs to be properly addressed when a lighting
installation is introduced, see last point above. This problem could be mitigated by clearly informing
occupants about the functioning and objectives of this lighting installation.
4.5 Conclusion
Besides visual and psychological effects, every form of lighting affects the human body via the ipRGC-
influenced pathway. The light patterns of exposure can be beneficial or non-beneficial for humans
depending on the setting relating to spectrum, intensity, duration, and timing of the resulting light
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exposure. At the same time, all existing visual and psychological aspects of lighting design remain
completely valid. Lighting schemes designed to achieve ipRGC-influenced effects by following the course
of daylight and that also follow existing guidance for lighting quality are likely to achieve beneficial
integrative lighting objectives. The many factors to be considered make this a challenging task. Thus,
the involvement of professional lighting designers who are familiar with the opportunities and risks
that are associated with ipRGC-influenced responses to light can lead to the best outcomes.
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Annex A
(informative)

Scientific background
A.1 General
A.1.1 Photodetection
Optical radiation that reaches the retina stimulates responses from at least five photoreceptive cell
types:
−2
— The rods respond at low ambient light levels (as low as approximately 0,005 cd m ) and saturate at
the levels typical of daytime. They are spread across the entire retina but are less numerous in the
fovea. They have low spatial resolution and do not detect colour; thus they are primarily responsible
for scotopic vision.
— Long-, medium-, and short-wavelength sensitive cones predominate in the fovea and are responsible
for resolution of fine details and colour vision. They are the primary photoreceptors responsible for
−2
photopic vision (>5 cd m ).
[4];[5];[6];[7];[8]
— Intrinsically-photosensitive retinal ganglion cells (ipRGCs) are irradiance detectors,
detecting the presence of light but not resolution of image details. As compared to the rods and
cones, the response threshold is higher and the temporal resolution is lower. The ipRGCs were
identified from a long line of research that focused mostly on the effects of night-time light exposure
on the suppression of the hormone melatonin, for which reason the active photoreceptive molecule
in these cells was named melanopsin. There are at least five subtypes of ipRGC, but the precise
[9];[10];[11];[12]
response characteristics and projections of each is not yet known .
Each photoreceptor has a characteristic spectral efficiency function, or action spectrum.
[64]
CIE S 026:2018 defined the action spectra for the five cell types, illustrated in Figure A.1 below. The
action spectrum for the ipRGCs, known as the melanopic spectrum, peaks at 490 nm.
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Key
X λ in nm 3 s (λ)
rh
Y relative spectral sensitivity 4 s (λ)
mc
1 s (λ) 5 s (λ)
sc lc
2 s (λ)
mel
[64]
SOURCE: CIE S 026:2018
Figure A.1 — Relative action spectra for the short (sc), medium, (mc) and long (lc) type cones,
the rods (rh) and ipRGCs (mel)
When the ipRGCs were identified in the early 2000s, it was thought that there were two separate
retina-brain systems, one for visual perception mediated by rods and cones, and one for so-called “non-
visual” effects. This is now known not to be the case, as evidence mounts for complex interconnections
[13]
between the cell types. For instance, the ipRGCs contribute to the regulation of pupil size as well as
[5];[7]
to the regulation of circadian rhythms . For this reason, it is incorrect to use the phrases “circadian
lighting” or “non-image-forming effects” or similar phrases to describe integrative lighting responses.
If one wishes to refer specifically to effects involving the ipRGCs, then the phrase “ipRGC-influenced
[64]
light (IIL)” responses is preferred [as specified in CIE S 026:2018 ].
A.1.2 Parameters influencing ipRGC light responses
Five parameters are known to affect IIL responses to light exposure: the spectrum, intensity, duration,
timing, and daily pattern of exposure. Integrative lighting recommendations will need to consider all of
these parameters simultaneously.
[64]
The melanopic action spectrum standardized in CIE S 026:2018 was, as noted above, derived
largely from investigations in which the usual night-time release of melatonin during darkness was
[14]
suppressed by exposure to light to varying degrees depending on the wavelength of the exposure.
At any given wavelength, the intensity of the light exposure also influenced the response. This dose-
response function was an essential element in demonstrating the existence of ipRGCs. Thus, to increase
IIL responses one might increase the intensity of exposure to the wavelengths to which the ipRGCs
are most responsive (as recommended in CIE 158:2009); however, this does not imply that one must
also reduce the intensity of exposure to other wavelengths, which support responses by the other
photoreceptors.
[13] [16]
As noted by Lucas et al. for pupil size and seen by Gooley et al. for melatonin suppression and
circadian phase resetting, the role of ipRGCs and other photoreceptors changes over the duration of
light exposure and in different ways depending on the intensity of the exposure. For instance, Gooley
[16]
et al. found that cone photoreceptors contribute to circadian phase resetting at low irradiances and
early in an exposure, but ipRGCs dominate at high irradiances and over longer exposures. However,
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exposures need not be continuous to be effective at eliciting IIL responses, at least for overnight
[17]
circadian phase resetting .
[18]
It has long been known that light responses vary depending on the time of the exposure, with the
system sensitivity depending on when the exposure occurs. Circadian phase resetting is the clearest
example of this. Light exposure before the nadir of the daily rhythm of core body temperature (i.e. in
the late evening or overnight) will delay the circadian rhythm, so that the nadir will occur later. Light
exposure immediately after the nadir of core body temperature (i.e. early morning) will advance the
circadian rhythm, so that the nadir on the following night will occur earlier.
The pattern of light exposure over the day has been known as an influence on subsequent IIL responses
[19];[20];[21]
for some time . Nonetheless, it remains unclear how to use this knowledge for lighting
applications, because the daily pattern of light exposure can vary widely from one individual to another
and the possible combinations of light exposure patterns are infinite. Except for individuals who
remain in one environment for nearly all of the time (e.g. in patients in
...