This certainly ancestral technique, in any case already attested in the first civilizations, uses light rays for care. We will expose its origins, its principles, its benefits, the means of putting it into practice, and its references.

Light therapy consists of daily exposure to artificial white light, called “broad spectrum”, imitating that of the sun or whose qualities are as close as possible to those of the sun. Also called heliotherapy or phototherapy, this therapy consists of exposing the face, but also other parts of the body, to light.

Its main goal is to treat disorders associated with disturbances in the internal biological clock, such as seasonal depression.

But light has other properties, other benefits, which have been used throughout the history of medicine: convalescence, healing, immunity… In addition, light of colors other than white has also proven its worth. for different health problems. In this case, color filters are used on the white lamp.

The main principles

Light therapy is part of the large family of phototherapies which use certain light sources (various intensities and colors, laser, etc.), sometimes combined with photosensitizers, to treat all kinds of ailments, in particular skin diseases (psoriasis Light therapy is mainly applied to disorders associated with disruption of biological rhythms, the best known of which is seasonal depression.

The internal biological clock, a powerful control center

By entering the body through the eyes, light plays a fundamental role in the regulation of circadian rhythms, that is to say those which occur over a period of about 24 hours (wakefulness-sleep, variations in body temperature and hormone levels, meals, etc.). These rhythms, which are managed directly by our internal biological clock, are called endogenous. However, many of them may not last exactly 24 hours. They synchronize with external environmental cues, including daylight, in order to maintain the correct rhythm. Light therefore participates in the constant regulation of our internal clock. This also controls other biological rhythms of varying length (the onset of menstruation in women, for example).

If the rhythms that are subjected to our internal clock are no longer in sync with day and night, we experience disturbing symptoms. The most glaring example is the experience of jet lag which makes us doze off during the day because our endogenous rhythms are convinced that it is night. Depending on the signals sent by the internal clock, the body can then secrete the sleep hormone (melatonin), during the day rather than at night. Depending on the case, we can “reset the clock” by exposing yourself to light at a specific time of the day, and thus “move forward or backward” its internal clock. Taking melatonin, also at the appropriate time, can also help to restore the regulation of the internal clock.

In addition, when light enters the eye, it is transformed into electrical signals which, sent to the brain, act on neurotransmitters. One of these, serotonin, often called the “happiness hormone”, regulates mood and governs the production of melatonin, responsible for wake-sleep cycles. Some scientific research indicates that the metabolism of melatonin is disturbed in people who suffer from seasonal depression. In fact, we observed in them an abnormally high level of melatonin during the day9, even if exposure to light would decrease its production10.

But light therapy also has other applications and beneficial effects:

• It activates cell growth
• It improves the immune system
• It stimulates the healing processes of the whole body

Against seasonal depression, and more

The main application of light therapy, and also the best documented scientifically, is in seasonal depression. This syndrome appears as winter approaches, as exterior light decreases, and has a detrimental effect on the internal biological clock in some people. The origin of this syndrome remains unknown. Light therapy is a recognized medical treatment to fight seasonal depression.

In the Nordic countries, 3% to 6% of people, and even up to 10%, according to some sources1-4, suffer from seasonal depression. They then present symptoms such as depressed mood, chronic fatigue, a drop in libido, an exaggerated need for sleep, difficult awakenings, binge eating or an abnormally high appetite, especially for sugar and carbohydrates. (bread, pasta, potatoes). In Canada, nearly 3% of the population would be affected by seasonal depression5, while 18% would experience a “winter depression” 6, characterized by disturbing symptoms, but less disabling than those of seasonal depression.

Light therapy is also used to treat other symptoms that may be associated with an imbalance in the internal biological clock, such as sleep disturbances and PMS, or to combat problems caused by jet lag or night work. It could also be useful in certain cases of depression such as postpartum (following childbirth) or nonseasonal depression in the elderly.

Light therapy could also have preventive virtues against these same problems. In particular, it could benefit people who experience a slight annual “winter blues” or who work all day without seeing the light of day, whether in an office or a factory. Dr David Servan-Schreiber mentions it, among others, in his book Guérir7 just like Dr Norman Rosenthal in Thirst for light8.

Contribute to the treatment of depression

A systematic review22 published in 2004 and reviewed in 2009 concluded, based on the analysis of 20 clinical trials (including 620 subjects in total), that light therapy shows modest, but promising, efficacy in contributing to the treatment of depression. seasonal.

In 2008, a systematic review was published based on 15 clinical trials23. Results are inconsistent when light therapy is used as the sole source of treatment. In contrast, in people on pharmacological therapy, adding light therapy treatments was effective in managing symptoms of depression.

Two clinical trials evaluated the effects of light therapy in people with major depression24-26. In these two trials, all subjects were also treated with an antidepressant. The results indicate that light therapy (10 lux) significantly reduced symptoms of depression and improved general well-being compared to placebo or medium intensity light therapy treatment (000 lux). The authors concluded that light therapy could be an effective therapeutic intervention to decrease symptoms of depression and could be used as an adjunct to pharmacological therapy.

Facilitate sleep (insomnia, early morning awakening)

By playing a role in the regulation of circadian rhythms, light therapy may help facilitate sleep27. The results of a few randomized clinical trials have shown that, compared to a placebo, light therapy sessions were effective in improving various sleep problems such as early morning awakening28, initial insomnia25 and phase-delay sleep syndrome (trend not falling asleep until very late at night) 30,31.

Regarding the simulation of dawn, a study32 carried out among 77 people concluded that this practice slightly increased the quality of sleep. However, the results of a pilot trial33 included in a systematic review34 indicate that the simulation of dawn, compared to a placebo, did not induce a beneficial effect on the duration of sleep in 13 subjects suffering from dementia.

Reduce the problems associated with jet lag (air travel and night schedules)

The results of a few clinical trials have revealed that, compared to a control group, light therapy may be effective in modifying internal biological rhythms and may therefore help reduce jet lag in air transport35-38 and improve sleep for night workers35,38,39, XNUMX. But more studies will be necessary before we can rule on the effectiveness of this approach.

Reduce depressive symptoms related to PMS

A systematic review40 published in 2005 identified 4 crossover clinical trials (55 subjects in all), which evaluated the efficacy of light therapy against depressive symptoms related to premenstrual syndrome. As these trials presented conflicting results, the authors conclude that there is currently no evidence of the effectiveness of light therapy in reducing the depressive symptoms associated with this disorder.

Reduce binge eating attacks associated with the influence of the seasons

Three clinical trials including 1741,3442 and 18 women43 with seasonal bulimia (increased seizures during winter) have been published. The results of the first 2 trials41,42 indicate that light therapy treatments could reduce the frequency of seizures compared to a placebo treatment. On the other hand, the results of the third trial43 did not demonstrate positive effects superior to placebo. Note however that the light intensity was, in this case, only 2 lux compared to 500 lux in the first 10. Finally, the results of a study without a control group000 carried out on 2 women indicate that light therapy could be effective in reducing the frequency of bulimic attacks.

Making it easier for older people with dementia to sleep

Light therapy may decrease agitation and improve sleep in older people with dementia45,46. In a small study, 48 people were exposed to artificial light for 90 minutes daily, for 8 weeks46. One half was a standard light source and the other half a light therapy lamp. Similar improvements in sleep duration were observed in both groups.

And much more…

By emitting a light with or without color filters on a particular area of ​​the body, about ten centimeters from the skin Light therapy has also been proven medically in the treatment of various problems:

• Chronic pain
• Wounds, wounds, ulcers, scarring
• Skin problems like acne and psoriasis (UVA therapy)
• Sports accidents, sports medicine
• Prevention of wrinkles, cellular aging
• Inflammation, arthritis
• Immune system

Where to do a session?

A session is generally carried out by making an appointment with a specialist therapist, sports doctor, naturopath.

Course of a light therapy session

To benefit from light therapy, you must be exposed daily to light with a defined spectrum and intensity. The light intensity must be greater than 2 lux in order to act effectively. For comparison, the brightness of a well-lit office is 000-300 lux and that of a fully sunny day can exceed 500 lux. The clinically recommended and recognized standard is a light exposure of 100 lux at eye level for 000 minutes each day.

For specific treatments on an area of ​​the body, the exposure is generally 3 minutes in white light, or for colors: 3 minutes of the main color followed by 30 seconds of the complementary color (for example, red then green, orange then blue, yellow then purple) or only 3 minutes for the indigo color which is balancing. For children under 7 years old, the duration is 1 minute then 10 seconds of the complementary color.

There is currently a consensus to recommend that treatment be done in the morning rather than in the evening. For the treatment of children and adolescents (who may also suffer from seasonal depression), the duration should be less, i.e., approximately 18 to 15 minutes per session, but it is important to be vigilant about possible symptoms of agitation caused by light therapy. If you think you are suffering from seasonal depression, it may be best to see your doctor for a diagnosis.

Usually results can be seen within the first week of treatment, but it usually takes 4 weeks of use before a clear clinical response and measurable biological changes are observed. Light therapy is effective in about 2 out of 3 patients with seasonal depression. In their case, the symptoms are reduced by 50% to 80% 18. This rate is comparable to that of antidepressants, but light therapy has fewer side effects and is less expensive.

Treatment begins as early as September or October and continues until spring. Some people may also feel the need in summer if it is gray for several days in a row. The most affected individuals may experience a return of symptoms only after 50 or 2 days of stopping. Thus, when the beautiful spring days come, it is preferable to decrease its exposure gradually.

Light therapy at home

Although some clinics offer the service, light therapy treatments are usually done at home. Lamps are just as effective as those used in the clinic, in lighting stores, in orthopedic appliance stores and in pharmacies. Make sure that the device does not emit UV rays and that the light intensity reaches approximately 10 lux (or 000 lux in the case of LED lamps). The light field should also be large enough so that you are not confined to a confined space during the exhibition. During a session, nothing prevents you from continuing your normal activities: reading, working, eating, television, etc., as long as the face remains bathed in light.

There are also low-light emitting masks that are applied directly to closed eyes while sleeping. They were designed, among other things, to be worn on airplanes, but have been the subject of relatively few studies30,31.

When treatment is prescribed by a healthcare professional, some insurance companies reimburse the cost of the devices. You can encourage your practitioner to contact the insurance company directly to argue that a light therapy lamp is cheaper in the long run than taking an antidepressant, while still being as effective.

Contraindications of light therapy

It appears that light therapy does not cause eye damage in the short, medium or long term47,48, however, some caveats are in order. Since ultraviolet (UV) rays can be damaging to the eye, make sure that the lamp does not emit it or has a UV filter.

On the other hand, although the side effects are rather rare (possibility of headaches, restlessness and insomnia), specialists agree to advise against this treatment for people suffering from certain eye problems (cataracts, retinitis pigmentosa). , macular degeneration and glaucoma), as well as certain diseases affecting the retina (eg diabetes). Likewise, people using drugs with photosensitive effects, including lithium, should not use them.

Likewise, avoid directly exposing the eyes to different colors.

The origins of light treatments go back to a very ancient time. Ancient civilizations, Greeks, Egyptians and Arabs already revered its healing effects on our health.

“Heliotherapy” was the first natural light therapy, successfully used as an effective medical treatment to prevent and cure various medical problems. Hippocrates the father of modern medicine (460 BC-370 BC) said: “Vis medicatrix naturae” – Honor the healing potential of nature, a key principle of natural medicines and in particular naturopathy.

In 1893, Danish physician Niels Ryberg Finsen developed one of the first devices capable of producing technically synthesized “sunlight”. Technically synthesized light has undeniable advantages: its intensity and the spectrum of the scattered light are controllable. From 1895 to 1903, he treated over 950 patients with lupus vulgaris (cutaneous tuberculosis) using technically synthesized and filtered “sunlight”.

In 1903 he received the Nobel Prize in Medicine for his research in phototherapy or light therapy and his exceptional therapeutic results. Dr Finsen is considered the founder of modern light therapy. In particular, he used violet light to which he exposed patients suffering from various infections.

Dr Norman E. Rosenthal, psychiatrist and researcher at the National Institute of Mental Health, was the first to demonstrate, in 1984, the link between light and depression13. It was he who defined the Seasonnal Affective Disorder, commonly known as SAD, which is translated as Seasonal Affective Disorder (SAD) or seasonal depression. In fact, the “discovery” of this type of depression is inseparable from the invention of light therapy itself.

It was by noting that exposure to broad-spectrum artificial light could benefit people with depressive symptoms during the winter season that Rosenthal was able to demonstrate the role played by light on circadian rhythms and mood, and so accurately describe this disease. Rosenthal has published several studies and books on the subject. It remains the essential reference in the field. He is part of the Society for Light Treatment and Biological Rhythms (SLTBR), an international organization of researchers who study light therapy and biological rhythms (see Sites of Interest).

In France, Doctor Christian Agrapart and his wife developed in the 1990s a method of care using colored lights (CEREC: Center for Study and Research on Energy and Color).

Strictly speaking, there are no certified “light therapy practitioners”. Light therapy is an approach used and recommended by many health professionals: doctors, neurologists, psychiatrists, psychologists, naturopaths, etc.

Light therapy and chromotherapy are particularly appreciated by therapists, but above all by patients, on the one hand for their simplicity of implementation, their absence of side effects, and on the other hand for their effectiveness, for example in the following problems where they have proven themselves (source: Jacques-Jean Quénet, ABC of chromatherapy)

Here are some practical examples of use:

• The depressive symptom (seasonal or not): 3 ‘(minutes) green then 3 ”” (seconds) at the base of the nose (eyes closed) and after half an hour, 3 minutes of white at the base of the nose . Once a week for the necessary time.
• Physical shock: 3 ‘red then 30 ”green on the area. After one hour, if the pain persists: 3 ‘blue then 30 ”orange
• Psychic shock: 3 ‘(minutes) green then 3 ”” (seconds) at the base of the nose (eyes closed)
• Wound (after disinfection of course): locally 3 ‘of white light. Or 3 ‘orange then 30 ”blue
• Healing: 3 ‘red then 30 ”green (session which can follow the previous one)
• Pain, inflammation, arthritis: 10 minutes of white light per day, or 3 ‘blue then 30 ”orange on the painful joint once a week
• Warming up, sports injury: a 10-minute session per day of white light on painful areas
• Osteoarthritis: 3 ‘green then 30 ”red once a week
• Colds, sinusitis: 3 ‘orange 30 ”blue on the nose, then 3’ red 30” green on the upper back.
• Cough: 3 ‘yellow then 30 ”purple in the throat and on the neck.
• Wrinkles: 3 ”of white light per day intensively, or 3 ‘blue then 30” orange once a week.