Public interest in RLT soared when NASA revealed that it used red light therapy on astronauts in orbit. 

In the following sections, we provide a literature review of a research project by scientists from various backgrounds, including:

The Medical College of Wisconsin

The Naval Special Warfare Group TWO

The NASA-Marshall Space Flight Center, AL 35812, (256) 544-2121

Departments of Neurology

Plastic Surgery and Neurosurgery

The following sections explain the unique impact of being in orbit on the body, how red light therapy helps compensate for the deleterious effects of weightlessness, and why top scientists at NASA support this protocol for their astronauts at the International Space Station (ISS) and for recovery treatment when astronauts arrive home.  

This provides somewhat of a foreground for the much more pervasive use of red light therapy in the consumer market. 

 

Space and Red Light Therapy: Treating For Cellular Vulnerabilities Due to Weightlessness 

Astronauts can stay in the International Space Station for up to six months. Given this length of time, it’s necessary to account for how the body degrades due to the lack of atmospheric pressure, (Nosrk, 2020). 

Microgravity environments have implications for human health that compound over time. The lack of outside medical care also means that NASA needs to use as many resources as it can to monitor and treat health conditions in space, (Childress et al, 2023).

NASA scientists already understood that extended weightlessness leads to weakened bones and muscles. They note that “muscle and bone atrophy are well documented in astronauts, and various minor injuries occurring in space have been reported not to heal until landing on Earth,” (Whelan et. al., 2000). This is why astronauts who have recently returned to earth are often seen having trouble even standing up and walking on their own before they undergo an exercise and recovery regimen.

However, the internal cellular effects were less well understood. Further “studies on cells exposed to microgravity and hypergravity indicate that human cells need gravity to stimulate cell growth,” (Whelan et. al., 2000). 

In other words, living for an extended time with no gravitational pull causes cells to act differently, and this slows down the body’s healing processes. 

Among the many options available, NASA has found that the use of LEDs “significantly improve(s) the medical care that is available to astronauts on long-term space missions,” (Whelan et. al., 2000). 

This is through the potential for “promot(ing) wound healing and human tissue growth,” (Whelan et. al., 2000). In their studies, NASA honed in on specific red light wavelengths, including 680nm, 730nm, and 880nm, which were found to be optimal for treatment. Later studies showed that higher wavelengths penetrated further into the body and promised similar therapeutic value (Algorri et al, 2021).

Using a spectrometer, researchers found that these wavelengths penetrated up to 23cm centimeters beyond the surface of the skin. This is what causes exposure to the mitochondria, resulting in its stimulation and faster healing, (Glass, 2021). 

 

The Discovery of Red Light Therapy’s Healing Properties 

Plenty of studies reveal the healing properties of red light therapy for medical patients, with strong indications that RLT has significant benefits for “civilian medical care, military situation, and long-term space flight” due to its wound-healing properties (Whelan et. al., 2000).

In one case, RLT treatment resulted in increased 2 fibroblast proliferation, growth factor synthesis, collagen production, and angiogenesis,” (Whelan et. al., 2000). In other cases, this FDA-approved treatment “quintupled the growth of fibroblasts and muscle cells in tissue culture,” (Whelan et. al., 2000). 

 

Aside from the documented healing properties, increased collagen production shows a consumer application for healthier skin and anti-aging properties. 

The researchers also displayed a preference for LEDs over lasers. Panels with many diodes can project light over a larger surface area of the body at multiple wavelengths, which have further therapeutic benefits when combined with additional wavelengths during treatment (Bayat et. al, 2022).

The researchers noted furthermore that the “potential benefits to NASA, military, and civilian populations include treatment of serious burns, crush injuries, non-healing fractures, muscle and bone atrophy, traumatic ischemic wounds, radiation, tissue damage, compromised skin grafts, and tissue regeneration,” (Whelan et. al., 2000).   

Whelan’s study also looks into how RLT may have applications for brain treatment. 

 

Findings on RLT Brain Treatment 

Although patients should first and foremost seek the guidance of a doctor, additional trials on RLT find that it may support treatment for brain tumors. 

Meanwhile, it should be understood that red light therapy is not intended to be used as the only treatment for tumors, but potentially alongside other treatments recommended by a medical healthcare practitioner. 

Some studies show that RLT wavelengths emitted by panels do penetrate the skull (completely noninvasively) and therefore may have healing properties for the brain. This has also been found in studies focused on treatment for Alzheimer's, (Ailioaie, et. al, 2023). RLT may also reduce brain inflammation, (Cardodo et al, 2022). 

The treatment of brain tumors has been conducted alongside the use of pharmaceuticals. “PDT consists of intravenously injecting a photosensitizer, which preferentially accumulates in tumor cells,” (Whelan et al., 2000). 

NASA has similarly used light-emitting diodes that may actually have superior skin and skull penetration. 

As light-diode technology has improved, manufacturers like SAIDI have produced panels with higher wavelengths, upwards of 850nm etc., which may penetrate even further beyond the surface of the skin for enhanced healing properties. 

 

References: 

Ailioaie, L. M., Ailioaie, C., & Litscher, G. (2023). Photobiomodulation in Alzheimer’s disease—A complementary method to state-of-the-art pharmaceutical formulations and nanomedicine?. Pharmaceutics, 15(3), 916.

Algorri, J. F., Ochoa, M., Roldan-Varona, P., Rodriguez-Cobo, L., & López-Higuera, J. M. (2021). Light technology for efficient and effective photodynamic therapy: A critical review. Cancers, 13(14), 3484. 

Bayat, M., Albright, R., Hamblin, M. R., & Chien, S. (2022). Impact of Blue Light Therapy on Wound Healing in Preclinical and Clinical Subjects: A Systematic Review. Journal of Lasers in Medical Sciences, 13. 

Cardoso, F. D. S., Salehpour, F., Coimbra, N. C., Gonzalez-Lima, F., & Gomes da Silva, S. (2022). Photobiomodulation for the treatment of neuroinflammation: A systematic review of controlled laboratory animal studies. Frontiers in Neuroscience, 16, 1006031.

Childress, S. D., Williams, T. C., & Francisco, D. R. (2023). NASA Space Flight Human-System Standard: enabling human spaceflight missions by supporting astronaut health, safety, and performance. npj Microgravity, 9(1), 31. 

Glass, G. E. (2021). Photobiomodulation: the clinical applications of low-level light therapy. Aesthetic Surgery Journal, 41(6), 723-738.

Whelan, H. T., Houle, J. M., Whelan, N. T., Donohoe, D. L., Cwiklinski, J., Schmidt, M. H., ... & Stinson, H. (2000, January). The NASA light-emitting diode medical program—progress in space flight and terrestrial applications. In AIP Conference Proceedings (Vol. 504, No. 1, pp. 37-43). American Institute of physics.

Norsk, P. (2020). Adaptation of the cardiovascular system to weightlessness: surprises, paradoxes and implications for deep space missions. Acta physiologica, 228(3), e13434.