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Everything you need to know about light therapy treatment

Jan 15, 2024

In ancient times, light and the sun were already recognized for their healing properties. Recent advances in neuroscience have reinforced this conviction by confirming that light has notable benefits on our health, particularly on our state of mind. As the winter season sets in, leading to a significant reduction in the duration of sunshine, the question arises: could light therapy be the ideal solution to combat the consequences of these atmospheric changes and maintain mental well-being optimal?

What is light therapy?

Light therapy, also called phototherapy, is a therapeutic approach using artificial light to treat various disorders and promote psychological well-being. Its fundamental principle consists of simulating natural sunlight in order to compensate for the lack of brightness, especially during the winter months characterized by shorter days.

Light therapy exerts an antidepressant effect while acting positively on various physiological aspects, such as vitamin D production, cardiac regulation and modulation of body temperature. In addition, this method aims to regulate the circadian rhythm and influence the secretion of hormones such as melatonin, associated with the sleep-wake cycle. The benefits also extend to alertness, cognition and mood .

A standard light therapy session involves exposure, within two hours of waking up, to a lamp with a power of 10,000 lux, located approximately thirty centimeters away, for a period of thirty minutes. This white light, free from ultraviolet , does not prevent the patient from carrying out various activities, such as reading or using a computer during the session. Therapeutic effects generally appear after one to two weeks of regular use.


Light therapy is particularly useful when the body loses its synchronization with its environment, thus offering solutions to various disorders. It is mainly effective in the following areas:

  • Treatment of seasonal depression , a condition often exacerbated by lack of natural light during the winter months.
  • For shift workers : it reduces disruptions to the circadian rhythm linked to atypical schedules.
  • Facing the aging process , where melatonin secretion decreases. Light therapy can reduce the harmful effects of this hormonal decline.
  • To correct phase delays or advances , sleep disorders linked to shifts in the sleep-wake rhythm.
  • In the case of jet lag, it offers a response to disruptions in the biological rhythm during travel.

These indications make it a favored therapeutic approach in Nordic countries, where short days and seasonal variations can significantly influence mental well-being. Studies have even demonstrated comparable effectiveness between light therapy and taking antidepressants in the treatment of seasonal depression, thus highlighting its central role.

Due to its equivalent effectiveness and the low presence of adverse effects , light therapy is often preferred as first intention. In the event of insufficient results, its use in addition to other treatments remains possible, thus offering a holistic approach to mental well-being.

Notable side effects

The strengths of light therapy lie in its naturalness and its effectiveness almost free of side effects, which, if any, generally appear mild and temporary.

Discomforts such as headaches, eye fatigue, irritability, insomnia (especially in the event of exposure in the evening) and feeling of dry eyes are among the occasional side effects.

To attenuate these reactions, the patient has the possibility of reducing the intensity and/or duration of exposure by opting for moderate light power (2500-5000 lux) and/or by carrying out short sessions (five to ten minutes per day) during the first few days. If adverse effects persist, it is recommended to take breaks during the session or move the lamp a few centimeters.


As a precautionary measure, a prior ophthalmological assessment and regular monitoring are recommended for patients with ocular pathology or risk factors for the retina, such as advanced age, diabetes or high blood pressure.

For safety reasons, the use of light therapy is not recommended in people taking photosensitizing treatments such as doxycycline, fluoxetine, lithium or quinolone antibiotics. People with bipolar disorder should avoid light therapy because it could trigger a hypomanic or manic state. It nevertheless remains indicated under medical advice during stable depressive periods.

Regarding pregnancy, light therapy may be considered in pregnant women with seasonal depressive disorder, providing a safer alternative to antidepressants. However, exposure to a light therapy lamp while breastfeeding is not recommended due to the potential risks of disrupting the baby's rhythms. The consequences of exposure to intense light in infants have not yet been sufficiently studied.

Which light therapy device to choose?

Faced with the variety of light therapy device offers, particularly on the internet, it can be complex to make an informed choice. However, several criteria must be considered to guide this selection. The light output of the device , measured in lux, is a crucial first parameter, with experts recommending a power of at least 10,000 lux for optimal results (especially in the treatment of disorders such as seasonal depression).

Another aspect to take into account is the color of the light emitted , with a preference for white light devoid of ultraviolet to avoid any risk to the skin and eyes. The use of a UV ray filter is necessary to guarantee safety during regular light therapy treatment, by counteracting the harmful effects of UV rays emitted by fluorescent bulbs (which otherwise have no advantage therapeutic).

Opting for a device certified to comply with safety and quality standards is strongly recommended, with particular attention paid to CE marking, essential to certify compliance with European standards. This regulation aims to protect users from the risks linked to negligent manufacturers, prioritizing price over quality. Any device without CE marking is likely to emit radiation dangerous to the skin and/or eyes.

Dawn simulator and light therapy: what are the differences?

The distinction between dawn simulator and light therapy is based on their objectives and mechanisms of action . Dawn simulators, although they do not belong to the category of light therapy lamps, use light as a means of establishing a gradual and gentle awakening.

Their main purpose is to act by stimulating the synthesis of cortisol through the eyelids (the eyes being more sensitive in the last hours of sleep). This increase in cortisol acts as a metabolic booster, facilitating the awakening process.

Although results in treating seasonal depression are encouraging with dawn simulators, they generally do not rival the effectiveness of light therapy lamps . Dawn simulators can nevertheless be recommended in addition to lamps in order to encourage awakening. Their gradual activation, starting a certain time before the scheduled wake-up time, allows a smooth transition to wakefulness.

In short, light therapy is emerging as a promising solution for improving mental well-being, particularly during the winter months when reduced sunlight duration can have repercussions on mental health. Based on natural principles, this therapeutic approach offers notable effectiveness with minimal and temporary side effects. Indications for light therapy cover a wide range of disorders, from seasonal depression to sleep disturbances, jet lag and the effects of aging. In addition, it is emerging as a preferential alternative to traditional drug treatments, with comparable or even superior results in the treatment of seasonal depression. However, it is essential to choose a certified light therapy device that meets safety standards, and to adjust the session according to individual needs to optimize the benefits of this therapy. Light therapy, used alone or in addition to other treatments, represents a viable holistic approach to promoting mental well-being.

References :

Sarah Freyheit S., pharmaceutical sciences. (2009). Light therapy and its main applications.

Bandiera C., Dr. Carli D., Dr. Berger J. (2019). Light therapy, first choice treatment.

Maruani, P.-A. Geoffroy. (April 2021). Light therapy for mood disorders.

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