Light, Mitochondria, and the Body's Oldest Conversation
A plainspoken, cited introduction to red light therapy... the science, the evidence, and the people practicing it well.
What is Red Light Therapy?
Red light therapy, known in the research literature as photobiomodulation or PBM, is the use of red and near-infrared light... roughly 620 to 900 nanometers in wavelength... to influence how our cells produce energy. The short version is this. Inside every one of your cells are mitochondria, and inside those mitochondria lives an enzyme called cytochrome c oxidase. It happens to absorb red and near-infrared light with remarkable selectivity (Hamblin, 2018; Salehpour et al., 2018).
When that light hits cytochrome c oxidase, a few things happen in quick succession... ATP production rises, nitric oxide gets released, and a small wave of protective signaling cascades through the cell (De Freitas & Hamblin, 2016; Ravera et al., 2021). It is a gentle nudge, not a sledgehammer. And like most gentle nudges in biology, the dose matters... too little does nothing, too much can backfire. Researchers call this the biphasic dose response, and it is worth keeping in mind whenever anyone promises that more light equals more benefit (Hamblin, 2017).
The story itself is not new. Humans have been sitting by fires and standing in the sun for a very long time. What is new is our ability to measure what the light was doing while we were warming ourselves. So it is with us... the ancient and the modern, describing the same event in different languages.
What the Evidence Actually Shows
A quick tour of where the science currently stands. Each claim below is rated by the strength of its supporting evidence. More detail lives on the research page.
Wound healing and tissue repair
Red (roughly 630 to 660 nm) and near-infrared (around 810 to 830 nm) wavelengths consistently accelerate healing in both animal models and human clinical trials. The effect is tied to upregulated energy metabolism and angiogenesis (Oyebode et al., 2021; Yadav & Gupta, 2017).
Childhood myopia control
Repeated low-level red light therapy at about 650 nm, delivered in short daily sessions, meaningfully slows the progression of myopia in children across multiple large RCTs. Long-term ocular safety is still being studied (Jiang et al., 2021; Cao et al., 2024; Ostrin & Schill, 2024).
Acne, scarring, and skin rejuvenation
Clinical trials consistently support red light (around 633 nm) for acne vulgaris and a broader set of dermatological conditions including photoaging (Mineroff et al., 2024; Ablon, 2018).
Cognitive function and neuroprotection
Transcranial PBM shows encouraging early results in animal models and small human trials for conditions involving mitochondrial dysfunction, including aging-related cognitive decline, Alzheimer's, and Parkinson's. Larger trials are still needed (Salehpour et al., 2018; Nairuz et al., 2024).
Muscle recovery and performance
Red and NIR light before or after exercise appears to support faster recovery and reduced soreness, likely through enhanced ATP production in working muscle (Miejska-Kamińska et al., 2025).
Metabolic health
A small but provocative line of research shows that 670 nm light can reduce postprandial blood glucose spikes in humans. Early and worth watching (Powner & Jeffery, 2024).
The therapeutic window, roughly 630 to 900 nm, is where our mitochondria listen most carefully. Red light (620 to 700 nm) reaches superficial tissues. Near-infrared (700 to 900 nm) goes deeper... bone, brain, muscle. Shorter wavelengths, blue and UV, do the opposite... they can impair mitochondrial function rather than support it (Núñez-Álvarez & Osborne, 2019; Osborne et al., 2017).
“Most plants require both light and dark to meet their furthest growth potential. So it is with us... a living body is a quiet negotiation with light, and we are just beginning to understand the conversation.”
Editorial
Where the Research Is Still Thin
It would be easy to write a glowing marketing page for red light therapy. A lot of sites do. This one will not.
The mechanisms are well understood. The short-term effects in wounds, skin, and myopia are well documented. Beyond that... the research is still young, the protocols are not standardized, and many studies suffer from small sample sizes, inconsistent dosing, or industry sponsorship (Grimes, 2024; Felician et al., 2023).
A few specific caveats to keep in mind:
- Dose matters, and more is not always better. The biphasic dose response is real. Excessive exposure can reduce benefit or cause harm (Hamblin, 2017).
- Long-term ocular safety data for pediatric myopia devices is incomplete. Some devices exceed maximum permissible exposure limits for the retina, and long-term studies are pending (Ostrin & Schill, 2024).
- Claims for serious diseases are not proven. Research for neurodegenerative and systemic conditions is promising but nowhere near the threshold needed to call it established therapy.
Our stance is simple. Read the evidence. Talk to a qualified clinician. Be patient with a field that is still maturing.
Start with the Research
A fully cited review of the current literature, organized by clinical domain and evidence strength.
Go to the Research Page