Pain Relieving Light – (How) Is it Possible?

About 15% of the population suffer from migraines and it is estimated that about 40% of all people with migraines would benefit from preventive treatment, but only 3–13% use it. Migraine is a huge burden for society and individuals. Migraines can be intensified by light, and some patients need to stay in a dark room until the attack is over. People with this type of photosensitivity show a clear preference for light color, specifically green, which has been shown to be more comfortable and even pain relieving in some cases. We will present a feasibility study with the aim of preparing a series of experiments to investigate if regular short-term green-light-exposure can prevent migraines. We will present findings from the literature, developed light equipment, and plans for future testing of migraine friendly light solutions.


Migraine
Migraine is a common but painful condition [1], estimated to be affecting around 15% of the world's population [2] Many people with migraine do not seek help even though they could benefit from preventative treatment [3].Migraines are characterised by powerful and debilitating headaches, often in the form of attacks lasting from hours to several days depending on the individual and situation [4].Migraines are also associated with other symptoms such as visual aura, nausea, vomiting and anxiety 1320 (2024) 012020 IOP Publishing doi:10.1088/1755-1315/1320/1/012020 2 [5][6].Since so many people suffer from this condition, migraines also represent big costs for society, the biggest part being costs of production-loss from sick leave caused by migraine attacks [7].The annual costs of migraine for society in EU is estimated to be around 50 billion euro [8].

The relationship between migraine and light
It is well established that there are individual differences between different people's light sensitivity, experiences of light, and light perception.Previous studies have shown that people with migraine are more sensitive to light in comparison to others, both during and between migraine attacks, and that up to 80% of patients are extremely sensitive to light during an attack [9][10][11].Many migraine patients therefore prefer to be in a dark room until the attack has passed.Extreme light sensitivity is called photophobia, and there is, as of today, no established way of treating such symptoms [12].Furthermore, other visual and light related discomfort from, for example, flicker, patterns, and color may also burden patients during migraines [11,13].Notably, it was found that even when they do not have headache, people with migraine have lower thresholds for detecting flickering light, and people with migraine with aura have the lowest thresholds of all [11].However, it is argued that light sensitivity for people with migraines does not automatically mean that patients need to or want to avoid all light [13].Instead, it may be more meaningful and helpful to examine what visual patterns, light frequencies, and colors that affect or discomfort migraine patients more than people without migraines.Migraine also seems to have seasonal variation [5,14], especially in arctic populations, related to the differences in sunlight [15].A study [15] showed that people suffering from migraine who experienced aura had more attacks in the bright spring and summer, used sunglasses to a greater extent than other patients, and even reported increased light exposure as an activating factor causing the migraine attack.Light was thus concluded to be an important explanation for the seasonal variation of migraine [15].
In a study from 1989, it was suggested that a significant part (30-60%) of migraine attacks were triggered by glare and light [16].However, this conclusion has since been criticized.The question of whether light itself actually triggers migraine attacks for some patients is difficult to answer with any certainty, as it is difficult to know if the attack has already started when the light discomfort is experienced by the patient, who then may interpret the light as the causing factor.
Regardless of what role light and illumination plays in causing migraine attacks, it is clear that it is an important parameter in many migraine patients' level of discomfort or comfort both during and between attacks [9][10][11]13].We therefore argue that more research is needed to understand how light circumstances can be improved to ease the suffering of people with migraines.

Green Light and Migraines
It is suggested in some studies that people with migraines have altered color vision [17][18].Furthermore, recent research found that people with migraine have preferences for green colored light [19].When examining how participating migraine patients responded to green light exposure over ten weeks, results of fewer headache days, less severe migraine attacks and even increased quality of life was observed [19].Noseda et al. [20] and Nir et al. [21] tested how exposure to lights with different colors affected patients during migraine attacks, and found that all colors but green seemed to intensify pain.Even more noteworthy was that some patients even experienced pain relief when exposed to the green light [20][21].Burstein et al. [22] suggest that this effect of the green light may be caused by the light reaching the part of the brain that regulates pain, through pathways from the retina that were just recently discovered.Given that light plays an important part for quality of life for many people with migraine, and that recent evidence suggest that green light may be less painful or even relieving for some people during migraine attacks, we argue that more attention needs to be paid to how light environment can be designed and adapted to help people with migraines.Not only does the relationship between green light and less pain need to be further examined and (possibly) verified through medical research, but the question of where, when and how light can be adjusted to help people with high light sensitivity needs to be addressed.

Aim
The long-term goal of this research project is to further understand and investigate how people with migraine perceive different lights and to verify the possible effect of green light on patients with migraines thoroughly.Before doing so one may first ask how and when green light should be exposed or administrated to the patient.In addition, for any treatment to be feasible, whether preventive or reactive, it needs to function with the patient's everyday life and needs.We believe that this means that light solutions adapted to the needs of light sensitive people need to be examined from several scientific perspectives including design, environmental psychology, and engineering.This paper reports on a pilot study departing from the above-mentioned work on green light and migraines.The aim of the pilot study was to, based on existing literature on light and migraine, develop green light prototypes for preventive migraine treatments for migraineurs, to be used in future studies with migraine patients.The purpose of this paper is to present the designed and reconfigured prototypes and discuss and suggest pathways for future research.

Method
The research team consisted of an interdisciplinary group of researchers and practitioners and a larger reference group to include the competence from a broad spectrum of scientific fields.The total competence involved in the project includes psychology, medicine, optics, light engineering, design, sociology and light researchers.
The prototypes were designed or reconfigured using an iterative work process including several steps.First, a literature review was conducted to synthesize existing knowledge on light and migraine as well as green light specifically.Afterwards, a series of meetings and workshops were held where alternative applications, treatments options and study design were discussed in the research team.After the first meetings and workshops, the designer in collaboration with light counsellor developed several prototypes, meaning different lamps with green light, to be tested.A workshop was held where the research team tried the lamps.After the workshop, a few of the lamps were selected to be developed further, with suggestions of improvements.The lamps were then exhibited at a migraine clinic in Gothenburg, where patients could, if they wanted, try the lamps, and leave a comment.In the final step, suggestions for approaches for future studies and next-step projects were developed by the research team.The overarching phases for the design method is summarized in the figure below.

Results
The results of the pilot study will be presented in three parts.First, green light prototypes will be introduced and described briefly.Secondly, the field test at the migraine clinic will be described.Thirdly, ideas for future research and testing will be presented.

Green Light Prototypes
For green light to be a feasible preventive treatment for migraine patients, illumination needs to be designed with the patient in mind, and how this green illumination can fit into everyday life needs to be considered.A person suffering from reoccurring migraines may not have the option to soak in green light everyday doing nothing for a long time, instead, the lamps may need to be designed to be compatible with performing different tasks or activities.In the design process for this pilot study, we asked how, then, can green light be administrated to migraine patients interested in trying this treatment?Luminaires come in many different shapes and forms, not only in terms of light characteristics such as strength, flicker, color etc, but also what type of lamp it is -a reading lamp, a lamp for ambient light, a ceiling armature and so on.Because of this, the designer of the research team had this in mind when developing different prototypes for preventive treatment.Note that some of the lamps were reconfigured from existing lamps.

The reading lamp
This lamp was configured from a standard IKEA lamp designed for reading.The idea was that a preventive light treatment, that is exposing oneself to green light to prevent migraines, can perhaps be combined with reading or other activities such as washing dishes.A moveable reading light can therefore be a viable option for green light exposure while everyday life of the patient goes on.
• Literature review • Workshops and meetings Phase 1 The ambient globe light Having a soft, ambient light for moments of relaxation as a form of preventive migraine treatment was also suggested in the form of this globe-like lamp projecting dappled patterns.The idea was that practising relaxation or meditation, serving the purpose of reducing stress, can be combined with green light exposure as a preventive routine.However, the light can also be used when performing other simple activities.The lamp can be placed for example in a bedroom in the privacy of one's own home, but also in a resting room at workplaces as a light option for those with light sensitivity.
Picture 2. The ambient globe light

The green light glasses
Another option for administrating green light is to wear these green light glasses.The glasses work best when patients decide to relax and do nothing for a while, as the glasses prevent them from seeing anything besides green light.The glasses could be used both preventively and perhaps also reactively during a migraine attack, if the patient finds it comfortable and relieving.

Field test at migraine clinic
The three lamps were exhibited for 7 weeks in 2023 at a clinic for migraine and headaches.The lamps were placed in a waiting room that also served as a place for rest for visitors when visiting the clinic.In this room we also put papers informing visitors that these lamps were developed and tested for research on migraine, and visitors were invited to leave written comments on what they thought about the lamps.The authors were not present while the notes were written.The comments were anonymous to the authors and the comments cannot be traced back to identify the commenter, thus no personal information was collected.The purpose of the field test was to get input on these lamps from people who suffer from migraine, to be able to get a first indication of the suitability of the lamps' design as well as ideas for further improvement that could be useful in future studies.As a proper medical study will require extensive ethical approval, significant funding and much planning, this initial field test served as a way to collect some initial response from the target audience used in idea generation for future development of the lamps and ideas for research design.Although our small field test for the feasibility study is not in any way statistically generalisable and the data is limited, it provides some initial insight on opportunities for future studies and design improvement from a qualitative point of view.13 different comments were collected, and a content analysis provided some common themes and words in the feedback from the field test.Comments were made in Swedish but have been translated by the authors.

Pleasant, calm, relaxing (Behagligt, lugnande, avslappnande)
The comments reveal that some of the visitors found the light comfortable and relaxing.The word 'pleasant' (behagligt) was mentioned nine times in the material, while the word calm (lugn/lugnande) was mentioned six times.Other words used were restful (vilsamt) and relaxing (avslappnande).Most of these comments seemed to refer to the ambient globe light, however some also referred to the other lamps.One comment even described a perceived pain relief from wearing the glasses "After the lighting and two minutes of wearing the glasses, I felt that the headache and pain in the eye was milder.(…)" -anonymous commenter.

Powerful, intense & need for adjustments
Other words used to describe the light in a different way were powerful and intense, mainly addressing the reading lamp and the glasses.These descriptions were used both in a positive and a negative sense, for example one comment described how the glasses gave a "powerful and comfortable light", while another stated that the light intensity of the glasses was much too strong and made them take them off immediately.One comment suggested that the glasses were too intense and that the effect would be better if the light was milder and that the light could be more covering.These descriptions indicate a need for the light to be adjustable to meet individual preferences and variation in light sensitivity.

Positive color aftereffect
Two comments described how the green light gave an aftereffect where they saw more pink colors after looking at the lamps.One of them described it as if the globe light had a pink color around it, while the other stated that they had tried the glasses, and saw everything in pink afterwards.Both comments indicated this as a positive experience, for example: "I wore the glasses and looked at the light (don't know if that was what I was supposed to do), but afterwards everything became pink and it had a calming effect on me" -anonymous commenter.

Uncertainty in longer effects
Comments also indicated that the commenters were curious about the effects of the lights during migraine attacks, as some preferred darkness, as well as long-term effects from using the light, illustrated by: "Pleasant light for the eyes.Would be interesting to try it a longer period to see the effect those days when migraine is at it's worst" -anonymous commenter.
In summary, the comments reflected mainly positive but also some negative reactions to the light, where the light was positively described as pleasant and calming while the negative seemed to be mainly about light intensity and that there was no way to adjust or dim the light strength.The lamps seemed to give certain color aftereffects, but the commenters were unsure how they would react during migraine attacks and if they would use the lights regularly.

Future plans for research and testing
Throughout the process of developing prototypes and discussing treatment ideas including light therapy, we identified several needs for future research.The effect of green light needs to be further investigated, and the treatment option of light for migraineurs need to be examined from different perspectives.Below, we present three different ideas for future research on green light and migraine.We believe different approaches are needed, and these suggestions should not be seen as replaceable by each other but rather complementary of each other, as they represent different types of research.

Investigation of light color preference in migraine patients
During the work process for developing prototypes, the question of exactly "what green light" is most comfortable for migraine patients came up.It was suggested that there may be individual differences in what green nuance people prefer, as well as other colors.We therefore suggest a small study investigating what light frequency preferences migraine patients have.A suggestion is to combine interviews on photophobia and light experiences with testing preferences through immersion in light.We suggest two alternative light technologies for this test.The first is a light dome, where the patient puts their head in a dome with colored light, providing a field of view without borders, which can be compared to the experience in a floating tank.The second is a light goggle that is simply put over the eyes, an experience similar to using VR-glasses.The patient can decide what frequency they find most comfortable, spend a short amount of time in the dome immersed in the light of their choice, or with the light goggles on, and then describe how they felt.This would give insight into what frequencies are preferred and how migraine patients experience colored light outside of their migraine attacks (since the light therapy is suggested as a preventive treatment).The research done on green-light [19][20][21] suggest that green light is experienced differently than other colors by migraine patients, findings that are both very interesting and important.However, more research is needed to examine and validate what potential there actually is in green light, if it is a relatively comfortable or even pain-relieving light for people with migraine or not.A cross-over study where migraine patients are exposed to preventive green light treatment in comparison with another, established effect such as cardio exercise or a prophylactic medicine, could be a way to thoroughly investigate this supposed effect further.A preventive green light treatment may be, for example, to regularly rest in green ambient light as a form of therapy.However, this may need to be compared to just resting, to verify whether the green light as such has an effect in addition to the possible effect of resting.Furthermore, if there is a positive "green light effect" for people with migraine, the question is whether that effect happens mainly during any of the phases of a migraine attack or perhaps as a preventive effect between attacks.This information is needed to understand how green light can be used in treatment of migraine.This means that another alternative would be to investigate what effect green light has during a migraine attack, using a similar crossover study design.Depending on what type of green light treatment is investigated, we suggest that different luminaires may be suitable for different studies.The green light glasses (see 3.1.3)may be more suitable for studies on acute green light treatment during migraine attacks, while the luminaires such as the ambient globe light (3.1.2) may be more suitable for investigating the effect of a preventive green light treatment.

Diary-based study of preventive and reactive green light treatment in the everyday life of migraineurs
How can light treatment for migraines possibly be successful and reach a high degree of diffusion among patients?We believe that this question is not only a clinical matter but also a question of user preferences and treatment design.We therefore suggest a user study on how green light luminaires can function and blend in the everyday life and practices of migraine patients.The prototypes configured through this pilot study have not yet been tested in real life settings, other than in an exhibition at a migraine clinic.We would like to lend these prototypes to migraine patients and ask them to report through diaries where in their homes they were placed, how they were used, when they were used (e.g. in relation to migraine attacks and everyday routines).We are also interested to know how the use was experienced by the patients, which could be investigated, for example, through interviews after the trial.This would give us an idea of further design and configuration improvements, as well as feedback on how compatible the use of green light is in everyday life of migraineurs.

Discussion
Migraine is associated with huge cost for society [8] and causes suffering for vast amounts of people around the world, and can in that sense be considered a major societal challenge.In addition to being painful and unpleasant for patients, migraine is often associated with social isolation [23].With this background, any action that can ease the burden from migraine is relevant to investigate.Taking this reasoning one step further, it is argued that migraine can be considered a social disease and that designing migraine-friendly workplaces, e.g., in terms of adapted light, is an act of social sustainability [24].The prototypes in this study may make a positive contribution to building migraine friendly environments, but further testing and research needs to be done.In addition, from a sustainability point of view, it is interesting to note that people with migraine in general seem to prefer less light and lower light intensity which indicates less electricity consumption during usage if people with migraine were to choose the design of light solutions.
The process of developing green light equipment, reviewing migraine literature and workshopping to figure out avenues for future research shed light on interesting questions and

Conceptual replication: Cross-over study of the effect of green light exposure on migraine patients
challenges.One such challenge is the complexity in practicality regarding treating migraine with light therapy.More design parameters than light frequency (color) must be considered to prevent visual stress among people with migraine [13].A number of light-oriented design actions in order to create a more migraine friendly work-place may be needed; e.g., avoiding lighting fixtures in which the light source is directly visible, opting for indirect lighting, and equipping workstations with adjustable lighting systems (direction, luminance and light temperature) and avoiding reflective surfaces [24].
The research process of configuring and discussing different options for how green light solutions can be administrated to migraine patients raises questions of where, how, and when migraine patients are able and willing to do light therapy and even what the term light therapy means.Light therapy may be performed in the home environment with specially designed lamps in an everyday context [16].It may also be conducted in a clinical setting.Furthermore, everyday light solutions, that we normally may not consider therapeutic, may have a therapeutic effect in the sense that they may reduce pain, e.g., by providing individual control of the light settings at work.
Since green light solutions may be perceived odd in a public place, what spatial contexts and activities are suitable to combine with green light?From green light flashlights on accessories such as rings or keychains, to green light settings on smart phones, to visiting special light facilities, the question of what people with migraine would prefer is still open [25].Tamsin and Bach [25] suggest that medical device design is a complicated and special process, and thus needs a specialized crossfunctional team to deal with challenges; and given that light solutions at least to some extent in the future may be considered a medical device, in the sense that it may reduce symptoms, a crossfunctional approach is needed.The importance of cross-functional teams are also more important the more technologically advanced the product is and the riskier the market is [26].A successful established light treatment that can be recommended by physicians of course needs to be medically sound, but it also needs to be compatible with patients' lives and needs, if it is to be a viable treatment option or complement other treatments.This requires both successful design of light technology itself, but perhaps also a wider understanding of everyday practices of people with migraine.We suggest four different contexts are important to consider, and most likely light solutions may be different in these contexts 1) Public environments such as work-places and public buildings 2) Home environments 3) Clinical environments such as waiting rooms 4) Well-being facilities such as spas, gyms and massage-rooms.Yet in each place, the light must fit in and possibly also be integrated in automatic light solutions.E.g., at the workplace a possible place where green light may be a feasible alternative used by migraineurs could be resting rooms.A resting room could be suitable for regular meditation or preventive care to maintain wellness, in this case a moment of green light treatment.For those who do not feel that they benefit from green light, it would be easy to switch to other light colors.Meanwhile, a globe light (3.1.2) or green light glasses (3.1.3)could be accessible for the migraine patient who wants to rest their head for a while during the workday.
Finally, a benefit of a wider, interdisciplinary research approach for studying green light treatment is that it may contribute to understanding of light sensitivity and individual differences in light needs overall, beyond migraine.We suggest that people with migraine may be considered an example of a specifically and sometimes extreme light sensitive group, however, not all light sensitive people suffer from migraine.It is also worth noting that not all people with migraine respond well to green light [18] and preference of light frequency may also vary between individuals.As such, increasing awareness of light perception and how it may affect mental and physical health, can be helpful to a wider audience and a wider category of applications.We suggest that there is a need for a complementary, more person-oriented light approach, where individuals of different needs are considered to a larger degree, to increase well-being and reduce light-related headache and other negative symptoms for example in workplaces.

Figure 1 .
Figure 1.Overview of work-and design process for pilot study.