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Red Light Therapy: Photosynthesis for Humans
Fishtown Medicine•7 min read
4.96 (124)

Red Light Therapy: Photosynthesis for Humans

Ashvin Vijayakumar MD

Medically Reviewed

Ashvin Vijayakumar MD•Updated May 23, 2026
On This Page
  • Beyond the Wellness Trend
  • How Does Red Light Work Inside Your Cells?
  • What Conditions Does Red Light Therapy Help With?
  • Proven, Promising, and Overhyped: A Straight Look at the Claims
  • Why Does Device Quality Matter So Much for Red Light Therapy?
  • Guidance from the Clinic
  • Is Red Light Therapy Different from a Sauna?
  • Actionable Steps in Philly
  • Common Questions
  • Can red light therapy hurt my eyes?
  • Does red light therapy tan my skin?
  • How often should I use red light therapy?
  • Is red light therapy safe during pregnancy?
  • How long until I notice results from red light therapy?
  • Can red light therapy help with hair loss?
  • Does red light therapy help with seasonal depression in Philadelphia winters?
  • What does a red light therapy session feel like?
  • Deep Questions
  • Can I use red light therapy if I have melasma or hyperpigmentation?
  • Does red light therapy interact with photosensitizing medications?
  • Is red light therapy safe if I have a thyroid condition like Hashimoto's?
  • Can I do red light therapy if I have a pacemaker or implanted device?
  • How does red light therapy compare to infrared saunas?
  • Can red light therapy help with chronic pain conditions like fibromyalgia?
  • Is red light therapy useful before or after a workout?
  • Can children use red light therapy?
  • Does red light therapy work through clothing?
  • Where can I find red light therapy in Philadelphia?
  • Can red light therapy reduce inflammation throughout the body, or only where the light hits?
  • How is red light therapy different from a tanning bed?
  • Should I take any supplements with red light therapy?
  • Scientific References

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TL;DR30-second take

Red light therapy (photobiomodulation) uses specific wavelengths of red and near-infrared light (660nm and 850nm) to recharge your mitochondria, the tiny power plants inside your cells. The light helps your cells make more energy (ATP), which can ease pain, calm inflammation, and speed up muscle and skin recovery.

Beyond the Wellness Trend

Red Light Therapy (also called photobiomodulation) is often sold as a beauty treatment. What it does is simpler and more useful than that. It is a tool for recharging the energy factories inside your cells.

You may have seen the glowing red panels on social media or in wellness studios. It is fair to wonder if this is just another trend. The mechanism, however, is grounded in well-studied biophysics. Plants use specific wavelengths of sunlight to make energy through chlorophyll. Your cells respond to specific wavelengths of red light (660nm) and near-infrared light (850nm) to make more ATP, the molecule your body uses for energy.

At Fishtown Medicine, we treat photobiomodulation (PBM for short) as a precise metabolic lever. We use it to support recovery and calm inflammation rather than treating it as magic.

How Does Red Light Work Inside Your Cells?

To understand why this works, look inside the mitochondria (the small energy factories in every cell) at an enzyme called Cytochrome C Oxidase, or CCO. CCO is the final step in the electron transport chain, which is the assembly line that makes ATP (your cellular energy currency).

Here is the problem. When you are stressed, tired, or inflamed, a molecule called nitric oxide can stick to CCO. That sticking slows down ATP production, almost like sand in a gear.

Photons (light particles) at the right wavelengths interact with CCO and dislodge the nitric oxide. Oxygen returns to its proper spot, and the cellular engine restarts. In a very literal way, you are unsticking the metabolic engine with light.

This is the work of Dr. Michael Hamblin, a leading researcher whose papers we rely on heavily.

What Conditions Does Red Light Therapy Help With?

PBM is FDA cleared for treating certain types of pain and signs of skin aging. The clinical effects often reach further than the skin.

  1. Skin and collagen. PBM stimulates fibroblasts, the cells that make collagen, which is why it can improve fine lines and scar texture.
  2. Muscle recovery. For patients who train hard, PBM appears to lower delayed onset muscle soreness (the achy feeling 24 to 48 hours after a workout) by calming inflammatory signals.
  3. Joint pain. PBM is a useful add-on for arthritis, helping reduce local inflammation without adding another pill.
  4. Thyroid support. Early evidence suggests PBM may help thyroid function in conditions like Hashimoto's (an autoimmune thyroid condition) by lowering local autoimmune activity. We treat this with tempered confidence and careful monitoring rather than as a settled fact.

Proven, Promising, and Overhyped: A Straight Look at the Claims

Red light therapy is neither a miracle nor a scam, and the honest version sorts the claims into three buckets. Most of the internet hype lives in the third one.

Worth considering, with reasonable evidence:

  1. Skin aging. Controlled trials back red and near-infrared light for modest improvements in fine lines, skin texture, and collagen density. This is one of the better-supported uses, and devices are FDA-cleared for it.
  2. Androgenetic hair loss. FDA-cleared low-level laser and LED devices have modest but documented regrowth data for pattern hair thinning, with laser-based devices tending to outperform LED. It works only while you keep using it, and it pairs best with proven treatments like minoxidil and finasteride.
  3. Localized pain and recovery. For joint pain, tendon trouble, and post-exercise soreness, the evidence supports short-term, modest relief as an add-on rather than a cure.
  4. Inflammatory acne. Light-based treatment has a place here, usually alongside standard care.

Promising but unsettled, from small or early studies:

Thyroid (Hashimoto's), fibromyalgia, and a mild whole-body anti-inflammatory effect from local treatment all have early signals and clear limitations. We use these with humility and monitoring, keeping them in a supporting role.

Overblown, where the claims outrun the data:

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Fat loss and body contouring, "detox," dramatic athletic-performance gains, cognitive enhancement, and whole-body cures for chronic disease. A glowing panel will not melt fat or detoxify you, and the marketing here runs well ahead of the science.

Two truths keep expectations honest. First, this is an adjunct rather than a replacement for the treatments that make the biggest difference: sunscreen and retinoids for skin, evidence-based medication for hair loss, and proper rehabilitation for pain. Second, dose matters, and more is not better. Photobiomodulation follows a biphasic dose-response, meaning the right wavelength, intensity, and time help, while too much can do nothing or even set you back. The right dose even depends on the target: energy-hungry tissues like muscle and brain tend to respond to lower doses, while skin, tendon, and cartilage need more. Many at-home devices are underpowered or used incorrectly, which is a big reason results disappoint.

Why Does Device Quality Matter So Much for Red Light Therapy?

A standard red light bulb does not do the job. Effective therapy comes from the right physics rather than a red glow. Clinical results depend on two variables.

  1. Wavelength. You want specific bands. Around 660nm (red) targets surface tissue like skin. Around 850nm (near-infrared, invisible to the eye) reaches deeper tissue like muscle and joints.
  2. Power density (irradiance). The device should deliver more than 50 mW/cm² (a measure of how much light energy hits each square centimeter of skin) so the photons reach the tissue you care about.

At Fishtown Medicine, we point patients toward medical-grade devices (such as Joovv or PlatinumLED) that publish verified output numbers.

Guidance from the Clinic

Dr. Ash
"I often describe this to patients as a passive workout for your cells. You might be standing still, but at the microscopic level, your mitochondria are ramping up their efficiency."

Our Perspective: We treat the body as one connected system. Rather than silencing a symptom, we want to give the body the energy resources it needs to repair itself.

Is Red Light Therapy Different from a Sauna?

Yes, they work in very different ways, and they pair well.

Sauna therapy relies on heat stress (a useful biological challenge called hormesis). You sweat, your heart rate climbs, and heat shock proteins activate.

Red light is photobiomodulation, a biochemical effect. You usually do not sweat, and the action happens at the level of electrons inside your mitochondria.

Many patients use both. Think of them as fire and light. Each one targets a different stress pathway, and the benefits stack.

Actionable Steps in Philly

How to bring light therapy into your routine.

  1. The free option. The sun delivers a strong dose of near-infrared light at sunrise. Get outside for 10 minutes before 8 AM. Morning light helps set your circadian rhythm (your internal sleep and wake clock) and gives you free PBM.
  2. Local access. Several Philly wellness spots, including Restore Hyper Wellness, offer clinical-grade PBM sessions. This is a low-commitment way to test whether the therapy helps your joint pain before buying a device.
  3. Home use. If the therapy works for you, a small panel for your desk or bathroom is a high-yield purchase. 10 minutes a day keeps the dose consistent.

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Scientific References

  1. Hamblin MR. Mechanisms and Mitochondrial Redox Signaling in Photobiomodulation. Photochem Photobiol. 2018. (The definitive review of the CCO mechanism).
  2. de Freitas LF, Hamblin MR. Proposed Mechanisms of Photobiomodulation or Low-Level Light Therapy. IEEE J Sel Top Quantum Electron. 2016. (Engineering perspective on light-tissue interaction).
  3. Hamblin MR. Mechanisms and applications of the anti-inflammatory effects of photobiomodulation. AIMS Biophys. 2017. (Detailing cytokine reduction pathways).
  4. Ferhatoglu SY, et al. Low-level laser therapy in the treatment of Hashimoto's thyroiditis: A randomized clinical trial. Photobiomodulation, Photomedicine, and Laser Surgery. 2020.
  5. Afifi L, et al. Low-level laser therapy as a treatment for androgenetic alopecia: A systematic review. Lasers in Surgery and Medicine. 2017;49(1):27-39.
  6. Huang YY, Chen ACH, Carroll JD, Hamblin MR. Biphasic Dose Response in Low Level Light Therapy. Dose-Response. 2009;7(4):358-383.
Medical Disclaimer: This resource provides clinical context for educational purposes. In the world of precision medicine, there is no "one size fits all." The right strategy must be matched to your unique lab work, physiology, and performance goals. Consult Dr. Ash to determine if this approach is right for you, particularly if you have chronic health conditions or are taking prescription medications.
Ashvin Vijayakumar MD (Dr. Ash)

Fishtown Medicine | Articles

2418 E York St, Philadelphia, PA 19125·(267) 360-7927·hello@fishtownmedicine.com·HSA/FSA Eligible

Frequently Asked Questions

Common Questions

Red light is very bright, though usually safe. Near-infrared light is invisible, so you cannot see how strong it is. Looking directly into high-power LEDs is not a good idea. Wear the protective goggles that come with your device every session.
No, red light therapy does not tan your skin. Tanning is a response to ultraviolet (UV) light. Red light therapy contains zero UV. Some early data even suggests red light may help repair the cellular damage that UV exposure causes.
For most goals, daily or every-other-day sessions of 10 to 20 minutes work well. Think of it like charging a battery. The effect builds up over weeks of consistent use, so steady, smaller doses beat one long session.
There is not enough human safety data on red light therapy in pregnancy to recommend whole-body use. Localized use over a sore wrist or shoulder is likely low risk, but talk with your obstetrician first. We default to caution any time the evidence is thin.
For skin changes like fine lines or scar texture, visible results typically appear after 8 to 12 weeks of regular use. For pain and recovery, many patients feel a difference within 1 to 2 weeks. Energy and sleep effects vary widely.
Some clinical data suggests red light therapy at 650 to 680nm can help with androgenetic hair loss (the most common type of hair thinning). FDA-cleared at-home caps and combs exist for this use. Results take 4 to 6 months and only continue while you keep using the device.
Red light therapy is different from the bright white light boxes used for seasonal affective disorder (SAD). Bright light therapy targets your circadian rhythm through your eyes. Red light therapy targets your mitochondria through your skin. The two tools solve different problems, so use a 10,000-lux SAD lamp for mood and red light panels for energy and recovery.
A session feels warm and bright. You stand or sit in front of the panel, usually for 10 to 20 minutes, with most of your skin exposed for full-body panels. It stays calm and painless the whole time, and many patients use it to read or meditate.

Deep-Dive Questions

Be cautious. Red and near-infrared light can sometimes worsen melasma (patches of darker skin, often on the face) in people who are prone to it. The heat from a strong panel may trigger more pigment. Start with very short sessions, watch your skin closely, and stop if patches darken. A dermatologist visit before starting is wise.
Yes, this matters. Some medications make your skin more reactive to light, including doxycycline, isotretinoin (Accutane), St. John's Wort, certain diuretics, and several chemotherapy drugs. Red light is mostly outside the wavelength range these drugs react with, but caution still applies. Always share your full medication list before starting therapy.
The early data on red light therapy for Hashimoto's thyroiditis is promising but limited. One Brazilian trial showed reduced thyroid antibody levels and reduced need for thyroid medication after a course of low-level laser therapy. We do not view this as a stand-alone treatment. It is one tool inside a careful plan that still includes labs, imaging, and your endocrinologist.
Red light therapy does not interfere with electronic implants because it does not produce magnetic fields or significant heat at depth. The light does not reach a chest pacemaker through skin and bone in any meaningful dose. Still, ask your cardiologist before starting, particularly if your panel sits over the chest.
Red light therapy and infrared saunas both use light in the infrared range, but they work very differently. An infrared sauna heats your body, which raises your core temperature and produces sweat, similar to a regular sauna. A red light therapy panel delivers specific wavelengths at higher intensity to drive a direct effect inside the mitochondria, with little heating. Use saunas for cardiovascular and detox-style benefits. Use red light for cellular energy and tissue repair.
Red light therapy may ease pain in fibromyalgia (a chronic condition with widespread muscle pain and fatigue), likely through its anti-inflammatory effect on muscle tissue. Results are modest rather than dramatic. We treat it as one piece of a broader plan that includes sleep work, stress care, and gentle movement.
Both timing options have data, but the science slightly favors using red light therapy before a workout. Pre-workout exposure (10 to 20 minutes) appears to lower muscle fatigue and improve performance. Post-workout exposure may speed up recovery and reduce soreness. If you only do it once, pick the time that fits your schedule. Consistency matters more than perfect timing.
Localized red light therapy for issues like a sports injury or acne can be reasonable for older children and teens, with parental supervision and short sessions. Whole-body panels for children do not have strong safety data, so we default to a no for routine use. Always loop in the pediatrician first.
No, red light therapy does not work through clothing. The fabric blocks most of the photons before they reach your skin. For best results, expose the area you want to treat directly. Eyewear is the only thing you should keep on during a session.
Several spots in Philly offer clinical-grade panels, including Restore Hyper Wellness in Fishtown and Center City, and a number of physical therapy clinics that use handheld devices for joint pain. For at-home use, Joovv and PlatinumLED are two of the more reputable brands with verified output numbers.
Local red light exposure can produce systemic effects in early animal and human studies, possibly through circulating signaling molecules and small extracellular vesicles. The effect is modest, so we view red light therapy as a strong local tool with a mild systemic bonus rather than a stand-alone anti-inflammatory drug.
Tanning beds use ultraviolet (UV) light, which damages DNA and causes the skin to produce melanin (the pigment that creates a tan). Red light therapy uses red and near-infrared light at a very different wavelength, contains no UV, and does not damage DNA the way UV does. The two devices can look similar, but their biological effects are opposite.
There is no required supplement stack. Some clinicians like to pair red light therapy with methylene blue or CoQ10 (a mitochondrial cofactor your body makes naturally) to support the same energy pathway. The data is interesting but not strong enough to recommend universally. We make these choices patient by patient, based on labs and goals.

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