Light therapy: medicine or not?

Zydre Guobyteadmin Published Updated

Light therapy (phototherapy) is often presented as a „natural cure“ for everything from mood-boosting to skin problems or even nail fungus. Light therapy produces positive biological effects because the body needs light to be healthy. Natural sunlight has been used as a treatment for centuries, although we now know that certain wavelengths can be both beneficial and harmful. For example, ultraviolet (UV) light therapy is used effectively to treat chronic skin conditions. However, exposure to ultraviolet light should only be done in moderation, as it is known to damage cells and even cause skin cancer. Based on years of research, scientists have identified a „therapeutic window“ of certain wavelengths – red and near-infrared light – that appear to have significant biological benefits without any of the previously mentioned side effects.

This article provides a clear "map" of the use of light therapy to make it easy to understand, Which light is for whom? and What device is best for this?.

A) Types of light (spectrum) and what they are used for

Different wavelengths (colors) of light and different doses cause different biological effects.

1) White bright light (SAD, mood, circadian rhythm)

This is a classic bright light therapy, most often used for symptoms of seasonal affective disorder (SAD / SAS), winter mood swings, and sleep rhythm "desynchronization". The most important thing here is not the "color", but brightness (lux) and usage time (Mayo Clinic).

Common practice protocol: 10,000 lux the device is used in the morning (within 1 hour after waking up) about 20–30 minutes, keeping a set distance, without looking directly at the light (Mayo Clinic).
It is also important to note that light boxes for the treatment of SAD are not regulated in the same way as medications, so it is worth choosing carefully.

2) Red light (about 620-700 nm)

Red light is often associated with photobiomodulation (PBM) is not just a "shining LED", but a method in which the dose and power. It is often mentioned for skin condition, discomfort, recovery, and modulation of inflammatory processes, but the results depend largely on the specific protocol and problem (PMC).

3) Near infrared (NIR) (approximately 780–1100 nm)

NIR is often bundled with red light (e.g. 660 nm + 850 nm). Marketing often emphasizes „deeper penetration“, but in reality the most important thing is precise parameters (wavelengths, irradiance, dose, distance, session frequency) and scope. The PBM literature often emphasizes that „one device fits all“ is an oversimplified promise (PMC).

4) Blue light (around 405–470 nm, often ~415 nm)

Blue light has antibacterial effects, which is why it is most often mentioned acne context (sometimes used alone or in combination with red). There are systematic reviews that analyze RCTs and suggest that blue light may be beneficial as an alternative or adjunct, although the magnitude of the effect depends on the protocol and the type of acne (PMC).

Important note: „therapeutic blue light“ is not the same as blue light from screens – the spectrum, intensity, and dose are different.

5) Green light (about 520-560 nm)

The green light is particularly interesting migraines on the topic: in clinical studies, green LED exposure has been associated with fewer headache days and improvements in some measures. This is not yet the "gold standard", but the trend has some basis (PubMed).

6) Yellow/amber (around 570-590 nm)

It is more commonly found in cosmetics and „skin soothing“ marketing. Clinical evidence is mixed here, so it is best viewed as an adjunct rather than a „treatment.“.

7) UV (UVA/UVB) – medical phototherapy

UV phototherapy (e.g., narrowband UVB) is a real medical practice, especially in the treatment of psoriasis, and is usually performed under the supervision of a specialist (American Academy).
It is important not to confuse it with a solarium: solariums emit more UVA and increase the risk of skin cancer - it is not a safe "substitute for treatment".

B) Types of light therapy devices (separately from spectrum)

Here are the devices according to their shape and purpose. The same spectrum can be found in several types of devices, so it is most convenient to choose as follows: first the problem → then the spectrum → then the device shape .

1) SAD light boxes (Light box)

  • Main goal: bright white light mood and circadian rhythm.
  • Most importantly: realistically achievable 10,000 lux at the specified distance, as little UV as possible, stable light flux (Mayo Clinic).

2) Therapeutic table/floor lamps (for SAD mode)

  • Often a convenient option for home or office (lighting + therapy).
  • It is necessary to check whether the „therapeutic mode“ really provides sufficient lux (Mayo Clinic).

3) LED panels (red/NIR for photobiomodulation)

  • Larger area devices for the body (back, legs, larger areas).
  • The most important thing is not the number of LEDs, but the parameters: wavelengths (nm), irradiance (mW/cm²), recommended dose (J/cm²) and distance (PMC).

4) LED masks (for the face)

  • Most often used for facial skin: red, blue, sometimes combined.
  • Mask ≠ panel: the mask is comfortable for the face, the panel often covers a larger area and often has a different "power" profile (depending on the model).

5) Handheld spot devices (for local application)

  • Small areas (acne, scar, joint, local skin area).
  • Convenient, but time-consuming if you need to illuminate a lot of areas.

6) Wearable devices (glasses and other wearables)

  • Intended for use while moving (more often - bright light modes).
  • Convenience is great, but it is important whether it actually meets the therapeutic parameters.

7) Devices for nail fungus (onychomycosis)

Lasers, light systems, and sometimes photodynamic techniques are commonly used here. Scientific results show „promising“ data, but also emphasize that protocols vary and more large RCTs are needed before this becomes a definitive standard treatment.
Photodynamic therapy (aPDT) and combinations with antifungal drugs appear promising in some reviews, especially as a combination regimen (PubMed).

8) Medical UV equipment (clinical phototherapy)

  • NB-UVB, excimer, etc. – usually in clinics or according to a doctor's prescribed protocol.
  • It is better not to start "UV therapy" at home without supervision on your own (American Academy)..

How to choose correctly (usually)

If the goal is winter mood, energy, sleep

Choose SAD light box (or a therapy lamp) that actually achieves 10,000 lux at the specified distance, and use in the morning for 20-30 min (according to tolerance) (Mayo Clinic).

If the goal is red/NIR (recovery, discomfort, skin)

Choose lady (for the body) or mask (for the face) and look at the parameters, not the marketing: wavelengths, irradiance, dose, distance, recommended protocol (PMC).

If the goal is acne

The most logical thing to do is: blue or blue+red light (masks or hand-held devices). There are systematic reviews that evaluate RCTs and show potential benefits, but consistency and realistic expectations are important (PMC).

If the goal is nail fungus

First of all, confirm the diagnosis (because not every "changed nail" is a fungus). Lasers/light can be considered as an additional measure, but there is still a lack of a uniform "golden protocol", so it is worth consulting with a specialist (PubMed).

Conclusion

Light therapy, also known as phototherapy, is becoming increasingly popular as a natural way to improve mood, reduce symptoms of seasonal affective disorder (SAD), and treat skin disorders. When choosing a light therapy device, pay attention to its key features and consult a specialist.

Light therapy is a group of tools where some areas (e.g., SAD light boxes, medical UV phototherapy) have very clear applications, while others (e.g., nail fungus devices) have promise, but require a sober assessment and often the involvement of a specialist.

You can read more about light therapy devices here. here.