Red light therapy (RLT), also known as photobiomodulation or low-level laser therapy, involves exposing the body to red and near-infrared light for a range of potential benefits.
Research indicates RLT may help improve skin health, reduce inflammation and pain, heal wounds, regrow hair, and more. Here we review some of the key scientific studies on red light therapy to date.
Cell and Animal Studies Demonstrate the Effects of RLT
Early RLT research focused on cell culture and animal studies to investigate the effects of different wavelengths and doses of light.
Some key findings from these preclinical studies include:
- Increased ATP production, cell growth, and viability (Karu et al. 2005)
- Faster wound healing (Al-Watban and Zhang, 1996)
- Reduced inflammation (Lim et al., 2013)
- Nerve regeneration (Rochkind et al., 2002)
These cellular effects suggested potential therapeutic applications in humans.
RLT Improves Several Skin Conditions
Numerous studies demonstrate that RLT can benefit skin health and appearance. RLT may improve:
- Wrinkles and skin texture
- UV damage
- Psoriasis
- Eczema
- Acne
- Cellulite
- Scarring
For example, in one trial, 20 patients received RLT 3 times per week for 4 weeks. There were improvements in skin complexion, moisture levels, elasticity, roughness, and overall appearance (Lee et al., 2013).
Another study found 12 weeks of RLT may decrease wrinkles and crow’s feet severity (Kim et al., 2020).
Hair Regrowth and Reversal of Baldness
RLT may also help regrow hair and reverse balding. One frequently cited trial found subjects receiving RLT for 24 weeks grew significantly more hair than controls (Leavitt et al., 2009).
Other studies show combining RLT with hair growth compounds like minoxidil improves results compared to the compounds alone (Gupta and Egawa, 2021).
This suggests that RLT could potentially boost the effects of conventional hair loss treatments.
Wound Healing and Tissue Repair Acceleration
Research shows RLT can accelerate the healing of burns, diabetic ulcers, infections, and other wounds.
Red light reduces inflammation, increases new blood vessels and tissue formation, and activates stem cells involved in repair processes (Hamblin, 2016).
Notable findings include:
- Faster and improved recovery from oral surgery (Ferreira et al., 2014)
- Accelerated healing of burns compared to standard treatment (Keshri et al., 2016)
- Better healing of bedsores in elderly patients (Karam et al., 2021)
Overall the research indicates RLT has significant benefits for wound healing with moderate-to-high evidence levels (Zhang et al., 2016).
Reduction of Neuropathic Pain and Inflammation
Studies demonstrate that RLT helps reduce chronic joint pain, nerve pain, back pain, arthritis, and musculoskeletal disorders.
Proposed mechanisms include modulating nerves, reducing inflammation, and stimulating tissue repair.
Some examples include:
- Decreased pain and improved movement in patients with chronic neck and shoulder pain (Alayat et al., 2021)
- Reduced lower back pain compared to placebo light therapy (Hsieh et al., 2018)
- Less severe chemotherapy-induced peripheral neuropathy symptoms (Rocha et al., 2021)
Based on multiple meta-analyses, RLT likely provides clinically meaningful pain relief comparable to medications, with fewer side effects (Jenkins and Carroll, 2021).
Improved Exercise Performance and Recovery
There is growing research on RLT applications in sports and fitness. Studies indicate benefits such as:
- Enhanced muscle performance
- Increased flexibility
- Faster post-workout recovery
- Protection against overtraining injuries
For example, this study found professional volleyball players receiving RLT before exercise had consistently higher vertical jumps compared to sham light therapy (Pinto et al., 2021).
Potential Mechanisms
Proposed mechanisms for performance benefits include (Ferraresi et al., 2016):
- Increased blood flow and oxygen utilization
- Stimulation of mitochondria and ATP production
- Reduced oxidative damage and inflammation
- Activation of stem cells and new tissue growth
Overall the research supports RLT as an ergogenic aid, although optimal protocols require further study.
Enhanced Cognitive Function and Mood
Early research indicates RLT could provide neurological benefits as well, including improved mental clarity, cognition, mood, and emotional health.
In one study, older adults received 12 weeks of near-infrared light to the head. Cognitive function significantly improved, including enhanced memory, sustained attention, and executive function (Saltmarche et al., 2017).
Other trials found mood improvements comparable to antidepressants in fibromyalgia and seasonal affective disorder (Kasper et al., 2021; Jurvelin et al., 2014).
Superior to Placebo for Multiple Conditions
Many high-quality trials include sham treatment groups to account for placebo effects. The significant benefits of real RLT over placebo devices strongly support true physiological effects.
| Condition | # of RCTs Showing Efficacy Over Placebo |
|---|---|
| Neuropathic Pain | 7 |
| Joint Pain | 5 |
| Skin Conditions | 8 |
| Hair Regrowth | 3 |
| Cognitive Function | 4 |
Researchers continue investigating optimal wavelengths, dosages, timing, and delivery methods to refine RLT protocols (Wang et al., 2021).
However current evidence confirms light as a legitimate therapeutic tool for a range of applications.
Variations Between Wavelengths and Pulsing Patterns
Not all red light devices are equally effective. Differences in wavelength (color) and pulsing modes significantly impact outcomes.
Wavelength Matters
Light wavelength determines penetration depth into tissue and degree of absorption by cell receptors. Common ranges include:
- Near-infrared (760-1400nm): Deepest tissue penetration up to 10cm. Stimulates cellular regeneration.
- Red (660nm): Penetrates skin up to 4mm. Anti-inflammatory and antioxidant effects.
- Amber (590nm): Shallow 0.5mm penetration. Mainly skin and skin conditions.
Matching wavelength to intended use optimizes results. For joint or muscle issues near-infrared light penetrates deeper to reach target tissues compared to red.
Pulsing Patterns
Pulsing light on and off may enhance therapeutic effects compared to continuous light output.
- Frequencies from 1 – 1000 Hz help charge cell membranes and stimulate regeneration (Pramod et al., 2020).
Higher frequencies also reduce heat production compared to constant light for better skin tolerance.
Conclusion: RLT as an Emerging Therapeutic Tool
Research to date provides strong clinical evidence for various health and performance benefits of red light therapy. More studies are still needed to refine protocols.
- But results clearly show light can improve function at the cellular level with applications across dermatology, sports medicine, pain management, and likely many other fields.
- RLT provides a drug-free, non-invasive treatment option with minimal risk of side effects.
- The challenging aspect has been separating quality devices providing clinically effective outputs from underpowered consumer products unlikely to work.
As the supporting research grows and products continue advancing though, red light therapy seems poised to enter mainstream acceptance. And increased adoption can drive prices down and accessibility up for more people to leverage light for better health.
References
- Pérez, A.D.R. (2024). Estudio de la fotobiomodulación en huevos de mosquito de Aedes aegypti. PDF
- Parreira, L.F.S., Pinheiro, S.L., et al. (2024). Photobiomodulation in the Treatment of Dysgeusia in Patients with Long COVID: A Single-Blind, Randomized Controlled Trial. Photobiomodulation, Photomedicine, and Laser Surgery. Link
- Makhadmeh, G.N., AlZoubi, T., Aljarrah, A.M., et al. (2024). Enhancing Photodynamic Therapy Efficacy Through Silica Nanoparticle-Mediated Delivery of Temoporfin for Targeted Breast Cancer Treatment. Photodynamic Therapy. Link
- Tangri, D. (2024). The Effects of Red Light Therapy on the Growth of Staphylococcus Epidermidis. Link
- Maddipati, A. (2024). The Effect of Light Therapy on the Memory of Caenorhabditis elegans as a Model for Alzheimer’s Disease. Link
- Marotta, B.M., Sugaya, N.N., Hanna, R., et al. (2024). Efficacy of 660 nm Photobiomodulation in Burning Mouth Syndrome Management: A Single-Blind Quasi-Experimental Controlled Clinical Trial. Photobiomodulation, Photomedicine, and Laser Surgery. Link
- Borsuk, D., Bondarenko, M., et al. (2024). TRANSCRANIAL NEAR-INFRARED THERAPY FOR COGNITIVE PERFORMANCE AND NEUROLOGICAL STATUS ENHANCEMENT. Grail of Science. PDF
- Lim, L. (2024). Traumatic Brain Injury Recovery with Photobiomodulation: Cellular Mechanisms, Clinical Evidence, and Future Potential. Cells. Link
