Migraine and Photic Stimulation:
Report on a Survey of Migraineurs Using Flickering
Light Therapy
David Noton, PhD

Users of a commercial light therapy device who were using it to treat migraine were surveyed prospectively to determine what results they had obtained after 30 days of daily use. Out of a total of 55 migraineurs, 44% reported that the frequency of their migraine attacks after the treatment was "Somewhat Less" or "Much Less" (under a conservative interpretation of these categories). Considering only the 28 migraineurs who stated that their migraine attacks were normally preceded by warning signs, 53% reported that the frequency of their migraine attacks was "Somewhat Less" or "Much Less". In view of the limited efficacy and undesirable side-effects of the available migraine preventive drugs, Photic Stimulation (flickering light therapy) must be considered a possible preventive treatment for migraine.©2000 Harcourt Publishers Ltd.

Introduction
A previous study by Anderson (1989) indicated that Photic Stimulation (light therapy with flickering light) appeared to be helpful in the treatment of migraine, both preventively and acutely. This finding was subsequently reinforced by anecdotal reports from users of a commercial light therapy device based on Anderson's work (the Lightmask, referred to below as "the light therapy device"). Since the efficacy and cost-effectiveness of migraine prophylactic drugs still leaves much to be desired (Ramadan et al, 1997), the possible preventive value of Photic Stimulation was of particular interest. Furthermore, the non-drug nature of the treatment makes it of particular interest for patients whose condition (eg. pregnancy) precludes the use of prophylactic drugs.

Aims
The anecdotal reports from the users of the light therapy device indicated that only some users experienced significant benefit, while others experienced little or no effect from the treatment. The present survey was intended to quantify what proportion of users experienced beneficial results and what level of benefit was achieved. A secondary aim was to determine which, if any, migraine symptoms were correlated with successful treatment.

Questionnaire
A copy of the survey questionnaire is included as Appendix A of this report. Section A of the survey asks about the nature of the subject's headaches. Section B asks about the subject's use of the light therapy device. Section C asks about the results experienced by the subject after using the device.

Many of the subjects completed Section A at about the time they received the light therapy device, though some did not complete it until a week or two later, due to various delaying circumstances. The subjects were contacted again approximately six weeks after receiving the device and were then asked to answer the questions in Sections B and C.

Most of the answers were obtained in direct telephone conversations with the subjects, but in a few cases it was only possible to contact the subjects by email or post, in which case the data was obtained from their replies on the survey form which they returned by email or post.

Subjects
All purchasers of the light therapy device from December 1998 through December 1999 were asked, at the time of purchase, whether they were buying the unit for treatment of migraine and, if so, whether they would participate in the survey. Of approximately 90 buyers who agreed to participate, 55 eventually completed the survey (48 women and 7 men, none under the age of 18). The others were eliminated for a variety of reasons: because their headaches were determined not to meet the medical criteria for migraine, because they had other conditions which overlapped and confused the migraine diagnosis (e.g. tumour), because they did not comply with the correct protocol for use of the device, or because they dropped out of the survey at some point. At least three attempts were made to contact each non-responsive subject and those who stated that they had dropped out because the treatment was not effective were included in the results in the appropriate category.

Protocol
Subjects were asked to use the light therapy device for at least 15 minutes per day for at least 30 days. Since the device shuts off automatically after 15 minutes, compliance with the time limit was easily obtained. Compliance with the 30-day duration was considered acceptable if subject had missed "only an occasional day" (Question B1). Since the subjects were paying customers, not volunteers or paid subjects, stricter enforcement of compliance was not possible.

When used at the factory settings, the light therapy device flashes at 30 Hz, each cycle consisting of 1/60 second with the left eye illuminated and the right eye in darkness and 1/60 second with the left eye in darkness and the right eye illuminated. The light is monochromatic red light with a peak wavelength of 654 nm, maximum intensity of approximately 0.75cd, and maximum radiant intensity of approximately 8.8 mW/sr respectively. Although the device always starts each session at the factory settings given above, the user can then adjust the frequency and brightness of the flickering light, using control buttons built into the device. However, from responses to Question B3 of the survey it was determined that almost all subjects used the device at the factory settings and that even those who experimented with other settings did not do so very often.

Interpretation of Subjects’ Responses
The questions in Section C of the survey, concerning improvement or worsening of subjects' migraine condition, allowed for only two levels of improvement, for example, "Somewhat Less" and "Much Less" (when assessing the frequency of migraine attacks) or "Somewhat Better" and "Much Better" (when rating their overall migraine condition). When taking verbal reports from subjects, the subjects' comments were interpreted in a conservative manner. Reports which were in any way dubious or vague about improvement were assigned to the category "About the Same". Only reports of a definate and meaningful improvement were assigned to the categories "Somewhat Less/Better" or "Much Less/Better", as appropriate.

In all conversations (and in the introduction to the questionnaire) emphasis was laid on the need to collect objective data. The subjects were repeatedly told that negative results were as valuable as positive results and that the aim was to gather valid data, not to collect endorsements or praise for the light therapy device.

Results

Validity of Answers to Questions in Section C
Of the four questions concerning the effects of using the light therapy device, only the first question, Question C1, regarding change in frequency of migraine attacks, proved to be a source of reliable and useful data. Answers to Questions C2 and C3, regarding severity and duration of attacks, proved to be suspect for two reasons: firstly, many of the subjects continued their previous regime of taking acute-treatment migraine drugs (such as sumatriptan) as soon as an attack threatened or started, making their answers regarding severity and duration largely irrelevant; and secondly, some of the subjects who experienced a significant reduction in migraine frequency now had too few attacks to properly judge their severity and duration. These problems with Question C2 and C3 created corresponding doubts about the answers to Question C4, regarding overall effect of using the light therapy device.

For these reasons, the results presented in this report are entirely based on answers to Question C1, i.e. results regarding changes in frequency of migraine attacks.

Change in Frequency of Migraine Attacks
Table 1 summarises the answers to Question C1 regarding the changes in frequency of migraine attacks after light therapy treatment for at least 30 days. It shows that 44% of the subjects reported that the frequency of their migraine attacks after treatment was "Somewhat Less" or "Much Less". This percentage held equally for female or male subjects (21 of 48 women, 3 of 7 men).