Positive Health Online

Light and Photic Stimulation

The importance of light for health is generally acknowledged, both in folk wisdom and in modern medicine. For example, insufficient levels of daylight cause seasonal affective disorder, whose treatment with bright artificial light is well established. Now many new forms of light treatment are starting to emerge, some made possible by modern technology, others perhaps a rediscovery of older, pre-technological therapies. Most of these new light treatments involve either coloured light or flashing light. They have been found to help a wide range of disorders ranging from medical conditions, such as premenstrual syndrome and migraine, to behavioural conditions such as insomnia and attention deficit disorder. Coloured strobic light is even being used to deepen and accelerate psychotherapy. This article will describe the particular form of light treatment known as photic stimulation.

The Light Mask

In photic stimulation gently flickering light is shone into the eyes for 15 to 30 minutes a day. The photic stimulation device is usually similar to sunglasses or a sleep mask, covering the eyes so as to shut out external light. Miniature lamps mounted in the device shine light into the user's eyes. The brightness and flash rate of the light are controlled by circuitry either inside the glasses or in a separate control box.

Alternatively, some photic stimulation devices are larger, self-standing devices that shine the light towards the user from a distance of a foot or more; these latter devices are generally intended for clinical use rather than home use.

Background: Early Work with Flickering Light

The effects of flickering light were noted even in historical times: the flickering light of flames in the hearth or of sunlight viewed through the spokes of a rotating wheel was observed to be relaxing. And in the 1960s and 1970s the consciousness-altering effects of strobe lights were an important component in the multi-media experience offered at rock concerts.

Portable photic stimulation devices were produced as a consumer item for home use in the 1970s and 1980s, but they were promoted mainly for recreational use and for relaxation and stress reduction. It only gradually became clear that they might have more significant therapeutic value. Described below are the most important of the studies that have transformed flickering light from a recreational amusement into a valuable therapy. We start with the most recent result, which is also one of the most carefully executed of the photic stimulation trials.

Photic Stimulation and PMS

Dr. D. J. Anderson and his colleagues at the Royal Postgraduate Medical School at Hammersmith Hospital in London, England, recently completed a trial of photic stimulation for premenstrual syndrome (PMS). Their results were reported in The Journal of Obstetrics and Gynaecology (17(1): 76-79, 1997).

Seventeen women with confirmed, severe, and long-standing PMS were treated with photic stimulation for fifteen minutes a day for three months. The light device consisted of a soft mask, which covered the eyes and which had red LED lamps mounted one in front of each eye.

The patients were asked to use the device at home for fifteen minutes per day, every day throughout their menstrual cycle. They recorded their symptoms daily for two menstrual cycles before treatment, three cycles during treatment, and one cycle after treatment was stopped.

On average the women experienced a 76% reduction in their PMS symptoms at the end of three months of photic stimulation (see Figure 1). This level of improvement is greater that that reported for any other PMS treatment, be it fluoxetine (Prozac), hormones, relaxation, or vitamin and herbal supplements. By the end of the trial most of the women could no longer be considered to have PMS and would not have qualified to enrol in the trial.

The trial was not blind and thus was open to possible placebo effects. However, the magnitude and persistence of the improvement make a purely placebo explanation improbable, especially since most of the women had previously tried other PMS treatments without success and were consequently sceptical of this new and unorthodox approach.

Photic Stimulation and Migraine

Previous to the PMS study described above, Anderson investigated flickering light as a treatment for migraine. In a preliminary study, published in the journal Headache, he found that of a total of 50 migraine headaches in seven patients 30 were "stopped" and all but one of the remainder were "helped." The median duration of headaches was reduced in all patients and the interval between migraine headaches appeared to be increased (see Figure 2). Typically the patients used the device for 30 minutes to terminate a headache, though subsequent work appeared to indicate that a 15 minute session every day was also effective as a preventative. It was during the work with migraine patients that it was accidentally discovered that the treatment was highly effective for PMS.

Both of Anderson's studies used a "protocol" or flash mode in which the light shone alternately in left and right eyes, ie, the left eye was illuminated for the first half of a cycle and the right eye for the second half of the cycle. The flash rate was initially set at 30 Hz (ie, 30 left-right cycles per second), but the patients had control of the rate and were instructed to adjust it for personal comfort. Some preferred rates close to 30 Hz, but others chose much slower rates, as low as 7 Hz; successful outcomes appeared to be largely independent of the flash rate. Brightness was also under control of the user, to be adjusted for comfort, but it was observed that generally brighter was more effective.

Other Disorders: ADD, Chronic Pain, etc.

In 1993 J. L. Carter and H. L. Russell of the University of Houston published in The Texas Researcher the results of a study of photic stimulation with learning-disabled boys aged eight to twelve. The study used an unusual protocol in which the frequency of the flickering light was varied every two minutes between 10 Hz and 18 Hz; the photic stimulation was also accompanied by auditory stimulation at the same frequency. The study showed significant increases in several intelligence measures. However, the number of sessions required was as high as 80.

N. Shealy and his colleagues at the Shealy Institute have performed a number of studies of photic stimulation for relaxation and for reduction and management of chronic pain. Their studies included measurements of levels of endorphins and other neurohormones and neurochemicals. They observed some quite dramatic changes as a result of 30 minutes of photic stimulation. Unfortunately most of these studies were not published in any peer-reviewed journal. Interesting studies of pain reduction in TMJ patients have also been jointly conducted by N. Thomas of the University of Alberta and D. Siever of Comptronic Devices Limited, though again these have been published only privately.

Strong anecdotal results have been reported by clinicians in several other areas, such as insomnia, fibromyalgia, and chronic fatigue and clinical studies are planned in these areas. Interestingly, all of the disorders mentioned above are those which have also been successfully treated with biofeedback, especially EEG biofeedback. As a result, photic stimulation is increasingly being used by EEG biofeedback clinicians as an adjunct to biofeedback (indeed, at a recent biofeedback conference it was remarked that many biofeedback clinicians are "closet flashers"!).

How Does Photic Stimulation Work?

How can something as simple as flickering light have such a beneficial effect? There are several theoretical explanations, none of which has been conclusively proven. Some researchers suggest that rhythmic flashing light drives and entrains the internal rhythms of the brain, speeding up slow brainwaves. This would be consistent with the EEG biofeedback connection mentioned above; however, those patients in D. J. Anderson's PMS trial who used the photic stimulation device at slow flash rates experienced symptom reductions equal to those using the device at higher flash rates.

Anderson believes that during PMS and other disorders the body's internal daily clock becomes de-synchronized from the external rhythm of day and night and that flashing light helps the clock to re-synchronize, perhaps by improving the general level of communication between different parts of the brain. If this is the case then photic stimulation should be an effective treatment for jet lag, but preliminary results in that area are not encouraging. Yet other researchers believe that the good effects of flashing light are due to increasing blood flow to the brain or to increasing the levels of various neurochemicals in the brain. Additional research will be needed to resolve this question.

Photic Stimulation Devices

There are a number of reputable manufacturers of devices for photic stimulation. The Forest Institute has had good experience with devices from Comptronics, LightMask, Mind Gear, and Photosonix (listed alphabetically). All of these manufacturers offer one or more devices which can implement the "Anderson Protocol", the particular flickering light sequences used in the PMS and migraine studies described above. (The LightMask has this protocol built into it.) The protocol used by Carter and Russell for learning disorder is rather complex, but could be programmed into some of the more sophisticated devices by a savvy user. The protocols used by Shealy and by Thomas and Siever can be programmed into any of the devices.

Further Information

The photic stimulation trials mentioned above are described in more detail, with full journal references, in a Forest Institute paper entitled Flashing Light: The Scientific Studies. Details of the protocols used in the various trials are described in a Forest Institute paper entitled Flashing Light: The Proven Protocols. These papers can be obtained from The Forest Institute.

Two excellent general references on the many forms of light therapy are:

• Breiling, Brian J. Light Years Ahead. Berkeley, CA: Celestial Arts, 1996.
• Liberman, Jacob. Light, Medicine of the Future. Santa Fe, NM: Bear & Co, 1991.
• Photic stimulation devices can most conveniently be obtained by ordering from the manufacturers by telephone, mail, or Internet. Order information for these manufacturers is as follows:
• Comptronics, Edmonton, Alberta, Canada: Lowest price approximately US$295. Tel: 1-800-661-MIND.
• LightMask, London, UK: Lowest price approximately UK £75 (incl. VAT), US$100. Tel: UK 0990 168 143, US 1-800-576-8038. www.lightmask.com   Email: info@lightmask.com
• Mind Gear, Mentor, OH, USA: Lowest price approximately US$150. Tel: US1-800-525-MIND. Web: www.mind-gear.com    mindgear@aol.com
• Photosonix, Cerritos, CA, USA: Lowest price approximately US$179. Tel: US 1-800-258-2566. Web: www.photosonix.com     mind@photosonix.com

Some of these devices are also available from mail-order catalogues. In the US, The Forest Institute has had good experience ordering from Tools for Exploration (1-800-456-9887), whose catalog offers devices from all of the above manufacturers (and several others).