Therapeutic Effects of Light on Various Psychological Disorders and Physical Diseases

Therapeutic Effects of Light on Various Psychological Disorders and Physical Diseases

Objective: To assess the therapeutic affect of light on various diseases and disorders.


The importance of light for health and vitality was perhaps more obvious in ancient times than it is today. People living close to nature have an immediate appreciation of the sun, perhaps even worship it religiously, in a way that is lost when one is insulated from nature by many layers of technology. Even a hundred years ago, the medical value of sunlight was still well appreciated. Wounds were known to heal more quickly and with less scarring when sunlight was used as a disinfectant. Tuberculosis clinics flourished in the high mountains of Switzerland. Rickets responded to sunlight. However, sitting around in the sunlight takes time and seems boring in today’s busy world, so the discovery of antibiotics in the middle of this century pushed aside most of these slow but natural cures. When light enters the eyes and strikes the retina, the resultant nerve signals pass not only to the visual cortex of the brain, so we can see objects, but also, over separate nerve pathways, to other brain structures including the hypothalamus, the pineal and pituitary systems, and the limbic system, causing hormonal and emotional effects.

Light Therapy Techniques:

Light therapy techniques range from the most simple and traditional to the most high-tech and sophisticated forms of light-assisted psychotherapy. These therapies may be categorized by the form of light used:

  • Bright Light therapy,
  • Pulsed Light therapy,
  • Colored Light therapy,
  • Colored Flickering Light therapy,

All these forms of light are applied to the eyes or experienced with the eyes. There are yet other forms of light therapy that involve shining light on other parts of the body, for example, direct light treatment of skin conditions or cancer tumors.

1) Bright Light Therapy

Taking a pill is sometimes cheaper and more convenient than staying at a sanitarium. The modern rediscovery of light therapy occurred in a more psychological context. Season Affective Disorder (SAD), also known as winter depression, was identified as a light deficiency problem, which could be corrected with exposure to bright light, especially on awakening in the morning. Of all the forms of light therapy, bright light treatment for SAD is by far the most thoroughly researched and the most accepted by mainstream medicine. “Light boxes”, sources of bright artificial light can be used for SAD sufferers to sit by during breakfast. There is even a battery-operated light “visor”, worn on the head, to shine light directly into the eyes while allowing the wearer to move about. The ultimate high-tech natural treatment is a light “alarm clock”, a dawn simulator, which turns on a gradually brightening light source, starting an hour or two before rising time and reaching its maximum when the (indoor) sun rises! Once the day is started, there is still the problem of inadequate and artificial indoor lighting in the workplace. Conventional fluorescent lamps emit light, which is deficient in many of the colors and wavelengths of natural sunlight. Replacing these lamps with full-spectrum fluorescent’s, more closely imitating sunlight can improve the performance.

2) Pulsed Light Therapy:

If bright light can have such an effect on the brain, mind, and body, it is to be expected that pulsed light would have even more effect. Pulsed light certainly grabs one’s attention; neurologically speaking, neurons tend to report only changing stimuli, quickly tiring of anything steady. So pulsed light might be considered more aggressive form of light therapy, for more severe conditions. This is known as phonic stimulation. Pulsed light is shone into the eyes either from a mask or goggles worn by the patient or by having the patient sit in front of a larger pulsed light source one or two feet away. Typically, the treatment is applied for 15 or 20 minutes per day.

3) Colored Light Therapy

In the 1920’s and 1930’s Dr. Harry Spitler developed a system known as Syntonic Optometry, which uses colored light, shone into the patient’s eyes, to treat a variety of physiological and emotional disorders, far beyond the traditional bounds of optometry. The light is shone into the patients’ eyes from a special light source equipped with a variety of colored filters. The underlying principle of this therapy is to balance the activities of the sympathetic and parasympathetic nervous systems using colors that are either stimulating or calming.

4) Colored flickering Light Therapy:

Colored pulsed light can be used as a catalyst in the process of psychotherapy. Here the more subtle emotional effect of different colors is combined with the penetrating effect of pulsed light to accelerate the therapeutic process of uncovering and bringing out deeply buried emotional material for processing and relief. Clearly, this procedure is highly dependent on the skill of the therapist; the selection of light color and flash frequency is an interactive process, involving a high level of awareness and even intuition on the part of the therapist

Light Therapy not involving the Eyes:

Some forms of light therapy involve shining light on parts of the body other than the eyes. The use of blue light as a treatment for neo-natal jaundice is a well-established medical procedure. A recent study reported that merely shining light on the backs of subjects’ knees was sufficient to alter the timing of the internal circadian body clock; this suggests that the effects of bright light on SAD may not be entirely mediated through the eyes. LASER light or colored light applied to acupuncture points in a modern-day version of traditional Chinese medicine. Another work done in Russia, over many years with thousands of patients, using a technique known as blood photo-modification in which blood is drawn from the patient, circulated though a glass tube where it is irradiated with laser light, and then returned directly to the patient; astounding results were reported for variety of diseases.

Narrow-band red light therapy in perennial allergic rhinitis and nasal polyposis:

Allergic rhinitis and nasal polyposis are common nasal diseases, but the available treatment modalities have only limited success. In this, patients with allergic rhinitis and with nasal polyposis can be illuminated (intranasal) at 660 nm for 4.4 minutes three times a day for 14 days (total dose 6 joules per day). Allergic rhinitis, if uncomplicated by polyps or chronic sinusitis, can be effectively treated by narrow-band red light illumination of the nasal mucosa at 660 nm, with marked alleviation of clinical symptoms. Whenever possible, candidates for phototherapy should be selected by endoscopic examination.

Light therapy side effects:

Light therapy has been considered a rather benign treatment with few side effects. A systematic report of side effects to light therapy using a light visor showed that approximately 20% of patients reported mild side effects, including headache, eyestrain, and feeling wired. A more controversial topic is the potential for prolonged bright light exposure to produce harmful effects on the retina. The intensities of light used in light therapy regimens are not considered harmful to the human retina based on short-term studies, but the retinal effects of long-term bright light exposure are not known.


Because of the potential harmful effects of long-term W exposure, light therapy devices should have W filters that block wavelengths below 400 nm. In a comparison light box study, cool-white fluorescent lights were as effective as full-spectrum fluorescent lights. Various light sources (including incandescent lights) are effective for treating SAD. Devices other than light boxes were also studied for light therapy. There was no relationship between the intensity of light and various measures of response to treatment, despite the fact that very low intensity light (60 lux) was used. This contrasts to most light box studies where a dear intensity-response relationship is found. The proximity of the visor light source to the eye may increase the amount of light that reaches the retina, as compared to a light box. Lux, a unit of illumination, may also not be the best measure of the biologic or therapeutic effect of light. There is increasing evidence that even low illumination can affect biologic parameters, so that for some patients, light as low as 100 lux may be therapeutically effective.

In this way, light therapy can be used for treatment of various physical diseases and Psychological disorders.

Prof. Prashant B. Patel, PICT, Pune-43

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