How deep does Light Therapy Reach and what does each wavelength of blue, green, yellow, red, and near infrared do?

Let’s take a closer look at how therapeutic light therapies work, their benefits, and the specific wavelengths involved. We’ll dive into blue, yellow, red, and near-infrared light therapies, discussing their uses, the depth they penetrate into the skin, and what makes them so effective.

Blue Light Therapy

Wavelength: 415 nm

Blue light therapy primarily uses blue wavelengths around 415 nanometers (nm). This specific wavelength is highly effective at targeting the bacteria responsible for acne and offers several other benefits.

Uses and Benefits

Acne Treatment
- How it works: Blue light penetrates the skin to a depth of about 0.5 mm. It targets Propionibacterium acnes, the bacteria that cause acne. The blue light induces a photochemical reaction, producing reactive oxygen species that kill the bacteria and reduce inflammation.
- Evidence: Research published in the Journal of Clinical and Aesthetic Dermatology shows that blue light therapy significantly reduces acne lesions and is a safe treatment for mild to moderate acne.
Neonatal Jaundice
- How it works: For newborns with jaundice, blue light helps break down excess bilirubin in the blood. The light converts bilirubin into a water-soluble form that can be easily excreted by the baby’s body.
- Evidence: The American Academy of Pediatrics states that blue light therapy is a standard and effective treatment for neonatal jaundice, preventing severe complications and ensuring safer bilirubin levels.
Skin Conditions
- How it works: Blue light also helps with skin conditions like psoriasis and eczema by reducing inflammation. It penetrates the upper layers of the skin, aiding in the reduction of redness and swelling.
- Evidence: Studies in Photodermatology, Photoimmunology & Photomedicine suggest that blue light therapy can effectively reduce inflammation and improve symptoms in various skin conditions.

Yellow Light Therapy

Wavelength: 570-590 nm

Yellow light therapy uses wavelengths between 570 and 590 nm. This range is particularly beneficial for improving skin health and mood, penetrating the skin to a moderate depth.

Uses and Benefits

Skin Rejuvenation
- How it works: Yellow light penetrates the skin to a depth of about 1-2 mm. It stimulates collagen production, improves skin elasticity, and helps reduce redness and sun damage.
- Evidence: The Journal of Cosmetic and Laser Therapy reported that yellow light therapy can enhance skin hydration, reduce wrinkles, and improve overall skin texture.
Mood Enhancement
- How it works: Yellow light can positively influence mood by affecting the body's circadian rhythms and serotonin production. It’s often used to treat mood disorders like Seasonal Affective Disorder (SAD).
- Evidence: Research published in Behavioral and Brain Functions indicates that yellow light therapy can improve mood and reduce symptoms of depression, particularly in those with SAD.
Wound Healing
- How it works: Yellow light therapy promotes wound healing by boosting blood circulation and lymphatic flow, aiding in faster tissue repair and reducing inflammation.
- Evidence: Studies in Lasers in Medical Science have shown that yellow light therapy can significantly enhance wound healing and reduce inflammation, making it a valuable tool for treating injuries and surgical wounds.

Red Light Therapy

Wavelength: 600-700 nm

Red light therapy, also known as low-level laser therapy (LLLT) or photobiomodulation, uses red light in the range of 600-700 nm. This type of light penetrates deeper into the skin compared to blue and yellow light.

Uses and Benefits

Wound Healing
- How it works: Red light penetrates the skin to a depth of about 5-10 mm, stimulating cellular activity and promoting tissue repair. It increases blood flow to the treated area, enhancing the delivery of oxygen and nutrients.
- Evidence: The Journal of the American Academy of Dermatology found that red light therapy significantly speeds up the healing process of wounds and reduces scarring.
Pain and Inflammation
- How it works: Red light therapy reduces pain and inflammation by decreasing oxidative stress and improving circulation in the affected tissues.
- Evidence: Research in Pain Research and Management shows that RLT is effective in reducing pain and inflammation in conditions like arthritis and muscle injuries.
Skin Rejuvenation
- How it works: Red light stimulates collagen production and improves skin elasticity, reducing wrinkles and promoting a youthful appearance.
- Evidence: A study published in Seminars in Cutaneous Medicine and Surgery confirmed that red light therapy improves skin texture, reduces wrinkles, and enhances overall skin tone.

Near-Infrared Light Therapy

Wavelength: 700-1200 nm

Near-infrared (NIR) light therapy uses wavelengths from 700 to 1200 nm. This light penetrates even deeper into the body, making it effective for treating muscles, joints, and deeper tissues.

Uses and Benefits

Muscle Recovery and Pain Relief
- How it works: NIR light can penetrate the skin to depths of 20-50 mm, reaching muscles and joints. It promotes cellular repair and reduces inflammation, enhancing blood flow and speeding up muscle recovery and pain relief.
- Evidence: A study in the American Journal of Physical Medicine & Rehabilitation found that NIR therapy significantly reduces muscle soreness and speeds up recovery after intense physical activity.
Neurological Benefits
- How it works: NIR light can penetrate the skull and potentially benefit brain health. It’s being studied for its potential to improve cognitive function and treat conditions like traumatic brain injury and neurodegenerative diseases.
- Evidence: Research in Frontiers in Neuroscience suggests that NIR light therapy can improve brain function, reduce neuroinflammation, and promote recovery after brain injuries.
Wound Healing and Tissue Repair
- How it works: NIR light stimulates cellular activity and promotes the repair and regeneration of damaged tissues. It’s effective in treating chronic wounds and injuries.
- Evidence: A study in Photomedicine and Laser Surgery found that NIR therapy significantly enhances wound healing and tissue repair, making it a valuable tool in medical treatments.

Safety and Usage Tips

Light therapy is generally safe, but here are some tips to ensure you use it correctly:

Consult a Professional: Before starting any light therapy, consult with a healthcare professional to ensure it’s appropriate for your condition.
Protect Your Eyes: Some types of light therapy, especially blue light, can be harmful to the eyes. Always use protective eyewear if recommended.
Follow Guidelines: Use the therapy device according to the manufacturer’s instructions or your healthcare provider’s guidance to avoid overexposure.