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LLLT Vs. LED Light Therapy: Clearing up Confusion (+Examining Therapeutic Benefits)

Today, I want to dive into a wellness optimization topic, specifically, the realm of light therapy. We'll explore some enlightening studies that shed light on the significance of various colors of light, including red, yellow, blue, green, and more. But before we dive into these captivating subjects, it's crucial to establish a solid foundation of knowledge about the physics of light and lighting equipment.


First, let's unravel the distinctions between LEDs and lasers. LEDs operate on the principle of electroluminescence within semiconductor materials. When an electrical current flows through a semiconductor, it energizes the electrons within, causing them to ascend to higher energy levels. As these electrons return to their normal states, they emit photons, which manifest as light. The specific properties of the semiconductor material determine the color of the emitted light.

One noteworthy characteristic of LEDs is their omnidirectional light emission, meaning they emit light in various directions. This feature makes LEDs suitable for applications where widespread or non-focused lighting is essential.

Going off of that is the notion that LEDs have low coherence. Coherence measures the alignment among light waves, where coherent waves have consistent phase relationships. LEDs exhibit low coherence because the light waves produced by different parts of the semiconductor are not synchronized, resulting in variations in their peaks and troughs.

Now, let's briefly touch on lasers before delving into power and other critical specifications relevant to light therapy.

Laser operation hinges on the concept of population inversion. In a laser medium, such as gas, crystal, or semiconductor, a significant number of electrons are initially excited to higher energy levels, leading to an inverted population distribution. This sets the stage for stimulated emission, where incoming photons with precise energies trigger the release of coherent photons by excited electrons. This process results in a cascade of identical-frequency, coherent, and highly focused laser beams.

In summary, lasers differ primarily in their initial population inversion and precise photon energy matching, which collectively produce the highly coherent and amplified laser output. This contrasts with the non-coherent light emission of LEDs.

Understanding these concepts is paramount when interpreting scientific data on light therapy. For instance, misrepresenting laser-based research as applicable to LEDs can lead to the proliferation of ineffective chromotherapy devices in the market. Furthermore, critical parameters like power and power density must be considered, regardless of whether the light source is LED or laser.

Power & Power Density

Power, in the context of lasers and LEDs, quantifies the rate at which light energy is emitted and is typically measured in watts (W). Power density or irradiance, on the other hand, quantifies the concentration of light energy per unit area and is measured in watts per square meter (W/m²) or milliwatts per square centimeter (mW/cm²). Power density is particularly crucial for laser therapy and certain red light therapy LED devices, as it indicates the intensity of the light at a specific point.


Now, let's briefly explore Low-Level Laser Therapy (LLLT), a type of laser therapy that affects biological systems through non-thermal means. In other words, LLLT promotes tissue regeneration, reduces inflammation, and relieves pain through a photochemical effect, where light is absorbed by bodily tissues and induces chemical changes.

LLLT on Wrinkle Reduction & Skin Hydration

Let's examine a study on LLLT for skin rejuvenation. In this study, a diode laser with a wavelength of 635 nm and 10 mW power was used for two 15-minute sessions per week for six weeks. The results showed a significant reduction in wrinkles, attributed to collagen upregulation and down-regulation of matrix metalloproteinase.

LLLT on Lymphedema

Another study focused on LLLT's effects on lymphatic flow and lymphedema. It employed a laser emitting light at 904 nm, with an energy density of 1.5 J/cm² during nine sessions over three weeks. After three months, the group receiving active LLLT experienced a significant reduction in upper-limb volume and improved quality of life.

In summary, both studies utilized lasers, but the first employed red light, while the second used infrared light. This showcases the diverse therapeutic possibilities of lasers and LEDs across different wavelengths, power levels, and dosages.

While numerous studies explore the potential of various light wavelengths, including yellow, blue, and green, we'll save those discussions for future episodes. Lasers and LEDs offer a myriad of therapeutic applications beyond ATP upregulation and red light panels, making further exploration of these topics intriguing and valuable.


Farivar, S., Malekshahabi, T., & Shiari, R. (2014). Biological effects of low level laser therapy. Journal of lasers in medical sciences, 5(2), 58–62.

Kim, H. K., & Choi, J. H. (2017). Effects of radiofrequency, electroacupuncture, and low-level laser therapy on the wrinkles and moisture content of the forehead, eyes, and cheek. Journal of physical therapy science, 29(2), 290–294.

Carati CJ, Anderson SN, Gannon BJ, Piller NB. Treatment of postmastectomy lymphedema with low-level laser therapy: a double blind, placebo-controlled trial. Cancer. 2003;98(6):1114-22.


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