Light therapy, a recognized tool

Light therapy literally means "healing with light". It consists of exposing the eyes to light with a specific intensity and spectrum close to sunlight. The lamp simulates exposure to sunlight and produces effects similar to sunlight. 

The effects of sunlight on mood have long been reported. We're generally in a better mood when the sky is blue! However, it's only recently that neuroscientists have been able to study its beneficial effects on mood disorders, sleep, alertness and cognitive functions.

Sunlight is involved in numerous mechanisms, such as synchronizing the internal clock and sleep-wake rhythms. In the brain, it inhibits the secretion of melatonin (the sleep hormone) and increases the secretion of serotonin (the happiness hormone).

How does it work? 

In practice, traditional light therapy uses a luminous material consisting of an ultraviolet (UV) filter that produces a fluorescent light emitting between 2,000 and 10,000 lux. There are various types of lamp on the market: standard light therapy lamps are the best-known and have proven their effectiveness, as have dawn simulators.

The effects of light therapy depend on light intensity, light spectrum, duration of exposure, time of day and an individual's own biological rhythms.

Light therapy is generally fast-acting: 1 to 2 weeks, with daily sessions. However, it is advisable to continue until spring, when natural sunlight increases, to avoid relapses.

Who is it for? 

Today, light therapy has proven effective for many disorders:

Seasonal depression, or seasonal affective disorder. Overall, the proportion of SAD patients responding favorably to light therapy is estimated at 65%.

Non-seasonal depression, in combination with antidepressants and/or psychotherapy. It also helps reduce the depressive signs associated with premenstrual syndrome.

Sleep disorders such as insomnia, chronic fatigue, or phase advances and delays, which either mean going to bed early and waking up early or, conversely, going to bed late and waking up late, impacting on quality of life. Light therapy helps to re-synchronize the biological clock.

Jet lag: exposure to light at the right times can reset the body's clock more quickly, avoiding the inconvenience caused by travel.

Are there any contraindications or side effects? 

As with any treatment, the advice of your general practitioner and/or psychiatrist is strongly recommended to ensure the best possible care.

However, light therapy is a safe therapy with no specific contraindications, provided you use the right equipment and good manners! However, some studies advise against light therapy during breastfeeding.

The advantages of light therapy are its naturalness, and its virtually side-effect-free effectiveness. Side effects such as nausea, dizziness or headaches are not systematically observed, and when they do occur, they are usually transient and benign, resolving spontaneously. To accelerate their disappearance, patients can reduce the exposure dose in terms of intensity and/or duration.

How do I get there?

You can talk to your GP about the possibility of reimbursement.

Light therapy lamps are also available over the counter for home use. In this case, choose your model carefully! It's best to choose a high-brightness lamp of around 10,000 lux for shorter exposure times. However, lower wattage lamps can be used for longer periods for reading or working. Considered a medical device, light therapy lamps must bear the CE mark for medical equipment (93/42/EEC).

As for wellness centers offering light therapy sessions, you should be aware that there is no specific training or label. You must therefore make sure that the lamps on offer comply with official standards.

In conclusion, light therapy is a natural, gentle therapy accessible to all, with proven beneficial effects. Combined with psychotherapy, it can bring real relief to some people.

Bibliography

P.A. Geoffroy, T. Fovet, J.-A. Micoulaud-Franchi, C. Boudebesse, P. Thomas, B. Etain, A. Amad, Light therapy and seasonal depressive episodes in bipolar disorder,

L'Encéphale, Volume 41, Issue 6, 2015,

Sarah Freyheit. Light therapy and its main applications. Pharmaceutical Sciences. 2009. hal-01733443

P.A. Geoffroy, Light therapy: when, how and for whom, French Journal of Psychiatry, Volume 1, Supplement 2, 2019,