It is scientifically proven: sunlight and the blue part of the light spectrum have a radical effect on our mood. The lower the brightness, the more you depress.

Unfortunately, this beneficial light is scarce in autumn and winter. Its absence can then cause some people to experience seasonal depression (or winter blues).

How does light affect the brain?

On a beautiful summer day, the light intensity can reach 100,000 lux (unit of illumination), while in winter, it can not exceed 500 lux, even in a well-lit room. These differences in brightness have a direct effect on the brain.

When the light enters the eye, a nerve message is transmitted by the retina to the epiphysis - gland located at the eye level but well back - nicknamed "the third eye". The light in the gland slows down the production of melatonin, the sleep hormone. This improves alertness and facilitates awakening.

Some studies also show that light increases the secretion of other cerebral chemicals, such as serotonin and dopamine (energizing and responsible for a feeling of well-being and euphoria, hence their antidepressant and regulating effect). 'appetite).

Seasonal Depression: Symptoms to Watch Out for

Everyone can be touched by the winter blues and it is important to recognize the signs:

• Persistent fatigue from October to the beautiful days.
• A desire to hibernate, to stay under the duvet and not to see anyone (not even your best friends).
• No more interest in his work, "aperitif" evenings or his yoga class.
• Regular breakdowns of pillow and libido.
• A significant increase in appetite with a clear penchant for chocolate bars, cheeses and dishes in sauce ... In short, a diet based only on "comfort food" (comfort food).

Light therapy: the miracle solution against the winter blues?

The main, seriously documented indication is to correct mood disorders resulting from seasonal depression and to resynchronize the disordered internal clock (by jet lag, night work or sleep disorders).

How? Thanks to the light therapy.

And the result can be radical: " I followed a 32-year-old patient who had the bad habit of falling asleep with chickens and getting up with the rooster crowing, she had no social life, says Professor Robert Poirrier, neurology department of the University Hospital of Liège.A cure of light therapy in the late afternoon has allowed to extend its cycle and recalibrate.

This therapy consists in exposing oneself to a white light imitating that of the sun and filtering the UV and infrared rays.

In France, there is no real "light therapist", but this approach is beginning to be advocated by sleep specialists, neurologists, psychiatrists, psychologists and practitioners of alternative medicine.

Many luminaires and luminotherapy lamps are now found in various stores (Phillips, Nature & Découvertes, Luminette).

The sessions, preferably in the morning, can be done by placing directly in front of a special lamp or by wearing light therapy glasses. In the case of lamps, the eyes must be oriented in the luminous field, without obliging themselves to fix the light source. You can read, watch a computer screen or TV.

Light, an anti-blues to use sparingly

Attention, there are still some contraindications. It is avoided to use a light therapy device if you suffer from pathologies of the eye (retinopathy, glaucoma, cataract, etc.) and bipolar disorders.

"Since we improve the mood, caution is still needed in manic-depressives, because when they get better, it can worsen their manic state, as any antidepressant would," says Professor Poirrier . Also treat treatments that increase sensitivity to light (antibiotics, lithium). In this case, it is better to consult a doctor before exposing yourself.

If you forget to turn off your light or remove your Luminette, you may end up feeling a little edgy, feel a headache or a slight eye irritation. The devices are not dangerous, provided they are tested and approved (the "CE Médical" label must appear on the product).

"Also beware of copies that circulate without medical validation, they can be cheaper but deceive the consumer, warns Marianne Karbassi, communication officer at Kiria.These counterfeits do not always emit the number of lux enough, sometimes prove dangerous ( no infrared and UV filters) and last significantly less than a real light therapy lamp programmed to live two or three years. "

In conclusion, it is better to buy your device in a pharmacy or in a serious shop.

Cures to start at the end of the summer

In the classic seasonal depression, north of the Loire, it is recommended to initiate treatments from late August-early September and to practice exposure half an hour every morning for a month.

At first, regularity is very important. It is even possible to feel positive effects in the first week.

If after two weeks, there is no relief, it is that we do not respond to treatment (20% of cases). If, over time, the depression returns, we can then consider booster sessions, more spaced at his own pace. During the session, the more you increase the light intensity, the more you reduce the exposure time.

With 10,000 lux, half an hour of light therapy is enough; with 2,500 lux, it's more like two hours.