Red Light Therapy for Men: Testosterone & Performance

Red light therapy for men’s health has become one of the most heavily marketed — and most overhyped — applications of photobiomodulation. Social media is awash with claims that shining a red light on the testicles will dramatically increase testosterone, improve fertility, and transform sexual performance. The reality, as with most things in health, is considerably more nuanced.

This article separates evidence from hype. We examine each claimed benefit — testosterone, fertility, erectile function, libido, and physical performance — against the actual published research. Where evidence exists, we cite it. Where it does not, we say so plainly.

Testosterone: what the evidence actually shows

The hype

The most prominent claim in the red light therapy men’s health space is that exposing the testicles to red or near-infrared light significantly increases testosterone production. This claim has been amplified by influencers, podcasters, and some device manufacturers. The typical narrative suggests that men can expect a 200–300% increase in testosterone levels with regular testicular PBM.

The reality

The evidence base for this claim is extraordinarily thin. Here is what actually exists:

The 1939 ultraviolet study (often misattributed)

The most commonly cited “evidence” for light therapy increasing testosterone is a 1939 study by Myerson and colleagues, published in Endocrinology. This study found that UV irradiation of the chest increased circulating testosterone levels in men, and UV irradiation of the genital area produced an even larger increase.

However — and this is critical — this study used ultraviolet light, not red or near-infrared light. UV and red/NIR light operate through completely different mechanisms. UV light has direct effects on steroidogenic enzymes and vitamin D synthesis pathways that are not shared by longer wavelengths. Citing this study as evidence for red light therapy’s testosterone effects is scientifically inaccurate.

Animal studies

A small number of animal studies have investigated the effects of PBM on testicular function:

Ahn et al., 2012 (Proteomics): This Korean study exposed rat Leydig cells (the testosterone-producing cells in the testes) to 670 nm LED light in vitro. The irradiated cells showed increased expression of steroidogenic enzymes and a modest increase in testosterone production compared to non-irradiated controls. However, this was an in-vitro study — cells in a dish respond differently to cells within the complex environment of a living testis.

Biswas et al., 1988 (Indian Journal of Experimental Biology): An older study that examined the effect of visible light on rat testicular function. Some wavelengths appeared to influence testicular steroidogenesis, but the study design and reporting make it difficult to draw firm conclusions.

Human studies

There are currently no published, peer-reviewed randomised controlled trials examining the effect of red or near-infrared light therapy on testosterone levels in men.

This is not a matter of negative results — it is a matter of absent data. The human evidence for testicular PBM increasing testosterone simply does not exist in the published literature as of early 2026.

Some small pilot studies and conference abstracts have reported preliminary findings, but these have not been published in peer-reviewed journals and cannot be evaluated for methodological rigour.

Honest assessment

It is biologically plausible that red or near-infrared light could stimulate Leydig cell function, given the in-vitro evidence and the known effects of PBM on mitochondrial activity in other cell types. Leydig cells are metabolically active and mitochondria-dependent — the enzymatic conversion of cholesterol to testosterone occurs partly within mitochondria. Improving mitochondrial efficiency could theoretically enhance testosterone synthesis.

However, biological plausibility is not evidence of clinical effect. Many interventions that work in cell culture fail to produce meaningful effects in living humans. Until properly designed RCTs are published, the claim that red light therapy increases testosterone remains unproven.

The responsible position is: It might work. There is a plausible mechanism. But we do not know whether it works, by how much, or whether the effect (if real) is clinically significant. Anyone claiming a 200–300% testosterone increase from testicular red light therapy is extrapolating far beyond the evidence.

Testicular red light therapy: practical considerations

Despite the limited evidence, many men choose to experiment with testicular PBM. For those who wish to do so, here are the practical and safety considerations:

Heat is the primary concern

The testes sit outside the body for a reason: spermatogenesis requires a temperature 2–4°C below core body temperature. Scrotal hyperthermia — even mild and temporary — impairs sperm production and quality. This is well established in reproductive medicine.

Red light therapy devices generate heat, particularly at close range. If the device warms the scrotal skin above normal scrotal temperature (approximately 34–35°C), any potential hormonal benefit could be negated or reversed by thermal damage to spermatogenesis.

Practical recommendations if you choose to try testicular PBM:

• Use a device with good cooling (fans) or position the panel far enough away to avoid significant warming
• Limit sessions to 5–10 minutes maximum
• Monitor scrotal temperature — if the skin feels warm, increase distance or shorten duration
• Never place the device directly against the scrotum
• Preferred wavelength: 630–670 nm (red) rather than NIR, as NIR penetrates deeper and may cause more internal heating

Which devices to use

Standard red light therapy panels can be used by angling the panel toward the groin from a distance of 30–50 cm. Some small tabletop panels or targeted devices are suitable. Avoid using high-power, close-range devices for this application.

Do not use devices specifically marketed as “testosterone boosters” that make unsubstantiated claims. These products exploit the evidence gap and are often overpriced for what they deliver.

Fertility and sperm quality

The evidence

Unlike testosterone, there is a small but legitimate evidence base for PBM affecting sperm quality — though almost entirely from in-vitro studies:

Salman Yazdi et al., 2014 (Lasers in Medical Science)

This Iranian study exposed human sperm samples to 830 nm diode laser light at various fluences (2–10 J/cm²). Irradiated sperm showed significantly improved motility compared to non-irradiated controls. The effect was dose-dependent, with moderate fluences (4–6 J/cm²) producing the best results.

Safian et al., 2016 (Photochemistry and Photobiology)

An in-vitro study that examined the effect of 620 nm and 530 nm light on human sperm. Red light (620 nm) at 4 J/cm² significantly improved sperm motility parameters (progressive motility, velocity) compared to untreated samples. Green light showed no benefit.

Preece et al., 2017 (Scientific Reports)

This study demonstrated that 633 nm light improved the swimming velocity of human sperm in vitro. The researchers attributed this to enhanced mitochondrial function in the sperm midpiece (where mitochondria are concentrated to power the flagellum).

Firestone et al., 2012 (Fertility and Sterility)

Red light (670 nm) applied to human sperm samples improved motility and viability compared to controls. The improvement was statistically significant at specific energy densities.

In-vivo evidence

Zan-Bar et al., 2005 (Animal Reproduction Science): This study exposed ram semen to 655 nm laser light. In contrast to the in-vitro results above, irradiated samples showed reduced sperm motility. This highlights the complexity of PBM dosing — the biphasic dose response means that the wrong parameters can produce opposite effects.

Human clinical trials on testicular PBM for fertility: None published as of early 2026. A small number of fertility clinics offer “laser-assisted sperm activation” as an IVF adjunct (irradiating sperm samples before insemination), but this is an in-vitro application, not a whole-body treatment.

Assessment

There is genuine, peer-reviewed evidence that red light at 620–670 nm can improve sperm motility in vitro. The mechanism is consistent with known PBM biology: sperm rely heavily on mitochondrial ATP production for motility, and red light stimulates mitochondrial function.

However, applying light to isolated sperm in a laboratory dish is fundamentally different from applying light through scrotal skin to sperm within the testis. The clinical translation remains unproven.

For men with unexplained infertility, testicular PBM is a reasonable experimental adjunct — unlikely to cause harm (provided heat is managed) and supported by a plausible mechanism. It should not be considered a substitute for evidence-based fertility treatments.

Erectile dysfunction

Mechanism rationale

Erectile function depends on adequate blood flow to the penile corpus cavernosum. Nitric oxide (NO) is the primary mediator of penile erection: NO activates guanylate cyclase, which produces cyclic GMP, causing smooth muscle relaxation and vasodilation in the penile vasculature.

Red light therapy stimulates nitric oxide release from endothelial cells and haemoglobin. This vasodilatory effect provides a plausible mechanism for PBM to support erectile function — particularly in men with mild endothelial dysfunction.

Evidence

Animal studies

Ryu et al., 2012 (World Journal of Men’s Health): This study investigated low-level laser therapy on erectile function in a rat model of cavernous nerve injury (a common consequence of radical prostatectomy). LLLT applied to the major pelvic ganglion area showed improved erectile responses compared to sham-treated animals. The researchers attributed this to neuroprotective and neurotrophic effects of PBM.

Jeon et al., 2021 (Photobiomodulation, Photomedicine, and Laser Surgery): Another rat study demonstrating that PBM (808 nm) improved erectile function after bilateral cavernous nerve injury, with evidence of increased neuronal nitric oxide synthase (nNOS) expression.

Human studies

There are no published RCTs of red light therapy for erectile dysfunction in men.

One small pilot study (Frangez et al., 2015, Lasers in Medical Science) examined PBM applied to the perineum in men with chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS). While the study’s primary endpoint was pain, some participants reported improved sexual function as a secondary outcome.

Assessment

The animal evidence is encouraging for post-prostatectomy ED specifically — a niche but important clinical scenario. The general ED evidence is essentially non-existent. The vasodilatory mechanism is plausible, but without human trials, red light therapy cannot be recommended as an ED treatment.

For men considering PBM for erectile function, it is important to note that ED has multiple potential causes (vascular, neurogenic, hormonal, psychological), and a one-size-fits-all approach is inappropriate. Any man with persistent ED should consult a urologist for proper evaluation rather than relying on unproven light-based interventions.

Libido

There are no published studies examining the effect of red light therapy on male libido (sexual desire) as a primary outcome. The claims made online about red light therapy increasing libido are extrapolated from the unproven testosterone claims — the logic being: “red light increases testosterone → higher testosterone increases libido.”

Since the first premise (red light increases testosterone) is unproven in humans, the conclusion (red light increases libido) is doubly unproven.

That said, some users report subjectively improved energy levels, mood, and vitality with regular PBM. If these effects are real, they could indirectly influence libido — but this is speculative and anecdotal, not evidence-based.

Physical performance and muscle recovery

Unlike the testosterone and libido claims, the evidence for red light therapy in exercise performance and recovery is genuinely strong. This is one of the best-evidenced applications of PBM, supported by a comprehensive meta-analysis.

Leal-Junior et al., 2015 meta-analysis

This systematic review pooled data from 46 studies and found that PBM applied before or after exercise:

• Before exercise: Significantly improved time to exhaustion, number of repetitions to failure, and peak torque output
• After exercise: Significantly reduced creatine kinase (muscle damage marker), blood lactate, and delayed onset muscle soreness (DOMS)

The effects were consistent across different exercise types, wavelengths (630–660 nm and 810–850 nm), and both laser and LED sources.

Practical application for athletic men

Red light therapy for exercise recovery is the most evidence-based application in men’s health. The protocol is straightforward:

Pre-exercise: Apply red/NIR light to the major muscle groups you plan to train, 5–10 minutes before exercise. Dose: 20–60 J per muscle group. This may enhance performance and reduce subsequent muscle damage.

Post-exercise: Apply red/NIR light to trained muscle groups within 1–4 hours after exercise. Same dose range. This accelerates recovery and reduces DOMS.

Wavelength: Both 630–660 nm and 810–850 nm are effective. NIR (810–850 nm) may be slightly better for deeper muscles due to greater penetration depth.

Device requirements: A standard red light panel with adequate irradiance (>50 mW/cm² at treatment distance) is suitable. Targeted devices (such as the Kineon Move+) are designed specifically for joint and muscle treatment.

Prostate health

Evidence

Red light therapy has been investigated for chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS), a condition that affects an estimated 8–14% of men at some point in their lives.

Ghalayini et al., 2014 (Lasers in Medical Science): This RCT enrolled 46 men with CP/CPPS. The treatment group received LLLT (830 nm) applied to the perineum, 3 times per week for 4 weeks. The LLLT group showed significantly greater improvements in pain scores (NIH Chronic Prostatitis Symptom Index) compared to the sham group at 4, 8, and 12 weeks.

Frangez et al., 2015 (Lasers in Medical Science): Another study on LLLT for CP/CPPS found improvements in pain, quality of life, and sexual function scores after 10 sessions of transperineal laser treatment.

These are small but well-designed studies that provide genuine evidence for PBM in CP/CPPS. The anti-inflammatory and analgesic mechanisms of PBM are well-established and directly relevant to this condition.

Red light therapy for benign prostatic hyperplasia (BPH) or prostate cancer: No evidence exists. These conditions should be managed by urologists using established treatments.

Protocol for men’s health applications

Given the varying evidence levels across different applications, here are evidence-based recommendations:

Muscle recovery and performance (strong evidence)

• Wavelength: 660 nm and/or 850 nm
• Dose: 20–60 J per muscle group (total energy)
• Timing: 5–10 minutes before or within 4 hours after exercise
• Frequency: Before/after each training session
• Device distance: 15–30 cm from skin

Chronic pelvic pain syndrome (moderate evidence)

• Wavelength: 810–850 nm
• Application: Perineal — target the perineum from below
• Dose: 4–8 J/cm²
• Frequency: 3 times per week
• Duration: 4–8 weeks minimum
• Important: Consult a urologist for proper diagnosis first

Testicular PBM / testosterone (insufficient evidence — experimental only)

• Wavelength: 630–670 nm (red — less thermal penetration than NIR)
• Distance: 30–50 cm minimum (to manage heat)
• Duration: 5–10 minutes maximum per session
• Frequency: Every other day maximum
• Critical: Monitor for warmth. If the scrotal skin feels warm, stop or increase distance
• Expectation management: There is no proven human benefit. Treat this as an experiment, not a treatment

Fertility support (preliminary evidence — experimental)

• Best evidence is for in-vitro sperm activation, not transcutaneous testicular irradiation
• If pursuing testicular PBM for fertility, follow the same cautions as the testosterone protocol above
• Consider in conjunction with — not instead of — standard fertility evaluation and treatment
• Manage scrotal temperature rigorously — hyperthermia is a proven sperm killer

Separating hype from evidence: a summary

Claim	Evidence level	Honest assessment
RLT dramatically increases testosterone	Very weak (in-vitro only, no human RCTs)	Unproven. Plausible mechanism but no clinical evidence. The 200–300% claims are not supported by any data.
RLT improves sperm quality	Weak–moderate (in-vitro human studies only)	Promising in-vitro evidence for motility improvement. No clinical trials of testicular PBM for fertility outcomes.
RLT treats erectile dysfunction	Very weak (animal studies only)	Plausible mechanism (NO release). No human trials. Not a substitute for urological evaluation.
RLT increases libido	None	No direct evidence. Secondary to unproven testosterone claims.
RLT improves exercise performance and recovery	Strong (meta-analysis, 46 studies)	Well-supported. One of the best-evidenced PBM applications.
RLT helps chronic pelvic pain	Moderate (small RCTs)	Genuine evidence from well-designed studies. Worth considering as an adjunct.

The bottom line

The men’s health red light therapy space is characterised by a stark disconnect between marketing claims and actual evidence. The testosterone and sexual health claims — which dominate social media and marketing — have the weakest evidence. The exercise recovery claims — which receive less attention — have the strongest evidence.

If you are a man considering red light therapy, the best-supported use of your device is for muscle recovery and exercise performance. The evidence here is robust, consistent, and published in peer-reviewed journals.

For testosterone, fertility, and sexual health, the evidence is either preliminary (fertility) or essentially non-existent (testosterone, ED, libido). This does not mean these applications will never be validated — the mechanisms are plausible, and future RCTs may demonstrate real effects. But as of today, claims about red light therapy transforming male hormonal health are running far ahead of the science.

Be sceptical of anyone who tells you otherwise — especially if they are selling you a device.

References

• Ahn JC, Kim YH, Rhee CK. The effects of low level laser therapy on the testicular steroidogenesis in vitro. Proteomics. 2012;12:72–78.
• Firestone RS, Esfandiari N, Moskovtsev SI, et al. The effects of low-level laser light exposure on sperm motion characteristics and DNA damage. Journal of Biophotonics. 2012;5(4):310–317.
• Frangez I, Smrke DM, Gunde Cimerman N. Chronic prostatitis/chronic pelvic pain syndrome treated with low-level laser therapy. Lasers in Medical Science. 2015;30(4):1199–1205.
• Ghalayini IF, Al-Ghazo MA, Harb OA. Low-level laser therapy for chronic pelvic pain syndrome. Lasers in Medical Science. 2014;29(3):1139–1146.
• Jeon SH, Lee HJ, Kwon TG, et al. Photobiomodulation therapy improves erectile function in rats with bilateral cavernous nerve crush injury. Photobiomodulation, Photomedicine, and Laser Surgery. 2021;39(3):201–208.
• Leal-Junior EC, Vanin AA, Miranda EF, et al. Effect of phototherapy on exercise performance and markers of exercise recovery. Lasers in Medical Science. 2015;30(2):925–939. doi:10.1007/s10103-013-1465-4
• Preece D, Chow KW, Gomez-Godinez V, et al. Red light improves spermatozoa motility and does not induce oxidative DNA damage. Scientific Reports. 2017;7:46480. doi:10.1038/srep46480
• Ryu JK, Cho CH, Shin HY, et al. Effects of low-level laser therapy on erectile function in rats with bilateral cavernous nerve injury. World Journal of Men’s Health. 2012;30(1):47–54.
• Salman Yazdi R, Bakhshi S, Jannat Alipoor F, et al. Effect of 830-nm diode laser irradiation on human sperm motility. Lasers in Medical Science. 2014;29(1):97–104. doi:10.1007/s10103-013-1276-7
• Safian F, Khalili MA, Karimi Zarchi M, et al. The effect of 620 and 530 nm wavelength lights on human sperm motility and viability. Photochemistry and Photobiology. 2016;92(6):888–892.