Astronauts, in the 1990s, took plants to the space station and found that red LED light helped them grow and accelerated photosynthesis. People are not plants, but research began to investigate whether these light frequencies could have an affect on human cells, and the answer is yes. The first red light therapy applications were precise to mitigate the harmful effects of space travel: muscle atrophy, poor wound healing, and loss of bone mass due to weightlessness. Light is composed of radiation with different wavelengths between 400-700 nm. The human eye can perceive between 380 and almost 780nm. In physical parameters: energy is proportional to frequency, from this law arises a basic order of colours, ultraviolet > violet > blue > green > yellow > orange > red > infrared. The wavelength of light is measured in nanometres (nm), i.e., the distance between the crests of the waves.
How Does Red Light Therapy Work?

Red light has similar effects on the human body as infrared light; both share mechanisms such as increased energy production in every cell of the body (increased ATP production). However, red light and infrared light differ in that the energy from red light is absorbed by the skin up to a depth of 25 mm, whereas infrared light can penetrate deeper. The same is true of light from the sun, which, among all its light spectrums, contains red wavelengths, which are beneficial to health. However, sunlight is a set of radiations that also includes UV light, which can be dangerous for the health of living organisms as it produces mutations in DNA. It is for this reason that it is preferable to use commercial devices for red light therapy. The simpler ones are weak and can penetrate only 3 mm into the skin, while the more powerful ones penetrate more, generating an effect from the inside out.
How Does It Affect Cells?

The cells that make up the tissues of the human body are made up of many organelles that have specific functions. One of the most important is the mitochondrion, which is responsible for producing energy from glucose and is thought to be able to absorb energy from light. Mitochondria have an enzyme called cytochrome c oxidase, which is responsible for energy production and is capable of absorbing red light with wavelengths between 600 and 1000 nm. This red energy acts as a photodissociator and causes molecules that limit the energy production of cytochrome c oxidase, such as nitric acid and carbon monoxide, to be released, allowing the mitochondria to use oxygen and continue to produce energy. Importantly, when the aforementioned molecules limit energy production, a stressful cellular environment is created in which cortisol plays a key role, so red light therapy is also anti-stress on a larger scale. On the other hand, red light has been shown to improve the structure of water found within the cytoplasm and elsewhere in the body. The surface tension of the cells is improved, and this promotes better ion exchange.
Benefits Of Red Light Therapy

The benefits to the use of red light therapy are still being studied, and it is a never-ending stream of fields and applications that are being discovered every day.
Increases energy:
- Produces energy from a natural source and makes you feel better
- Increases sense of well-being and self-confidence.
- It makes you feel good, you have more positivity, you are more cheerful, it helps you relate to others.
Helps with skin problems:
- Skin problems such as acne respond best to red light wave levels near 650 nm.
- This light increases the production of collagen and ATP in the skin.
Activation of blood circulation:
- Red light therapy increases circulation as it penetrates the skin layers, transporting more oxygen and nutrients to the cells and tissues.
- It results in faster muscle recovery and increased elimination of toxic waste.
Anti-ageing:
- Red light therapy is used to achieve a more youthful appearance and to treat hair loss.
- It activates the creation of collagen in the skin, reducing fine lines and wrinkles.
- Red light therapy can also improve skin tone, including texture.
Accelerates recovery and prevents muscle soreness:
- Red light therapy prevents muscle soreness and helps with recovery after exercise.
- The key is the correct application of joules per square centimeter.
Promotes wound healing:
- Within the spectrum of 600 to 1,300 nanometres, it stimulates the skin, wound, and tissue healing through cell activation.
- Red light therapy helps skin cells to heal by stimulating and regenerating fibroblasts, keratinocytes, and modulating immune cells.
- This therapy promotes more blood production and brings it to the skin; this causes faster healing due to the oxygen and nutrients coming from the blood.
Red light therapys inflammatory effects may help against inflammation caused by Coronaviruses. Some scientific studies suggest the possibility that red light may be a high-potential treatment modality for this virus due to its anti-inflammatory effect on the lungs and its high potential to decrease the level of pro-inflammatory cytokines.
Risks of Red Light Therapy

Red light therapy is currently approved by different health organisations around the globe and is considered completely safe. The important factor is to receive a healthy amount of joules and a device of the best quality. Although the benefits of red light therapy have been proven to be safe, you have to be careful what you buy because when one product is very successful, good but also poor-quality replicas are released onto the market. Some devices use therapeutically undesirable hertz or flashlight, which can be dangerous for anyone with a history of epilepsy.