Red Light Therapy and Testosterone | LightTherapy.no
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Red Light Therapy and Testosterone: What the Science Says
Red light therapy (rødlysterapi) may support testosterone production in men by stimulating the mitochondria inside Leydig cells — the testosterone-producing cells in the testes — to generate more ATP, the cellular energy those cells need to synthesise hormones. The evidence is promising but still emerging. Animal studies show a clear effect. Human data is limited. But the biological mechanism is solid and the Norway context makes this particularly worth understanding.
There is a question I get asked more often than I used to. Men come to me, sometimes a little sheepish about it, and want to know whether their red light panel might do something for their energy, their drive, their hormones. And for a while I gave a fairly cautious answer.
I am still cautious. But I have been reading more closely, and the honest answer is more interesting than I thought.
Let me back up and start with something that almost nobody talks about when they discuss testosterone: the role of light.
Testosterone Is a Circadian Hormone
Here is something that tends to surprise people. Testosterone follows a very tight daily rhythm. It peaks in the morning, typically between 7am and 10am, and drops significantly through the afternoon and evening. This is not a small variation. We are talking about levels that can be 30-50% higher in the morning than in the evening.
Why does this matter? Because that daily pulse is regulated by your circadian clock. And your circadian clock is regulated primarily by light.
Dr. Jack Kruse has written and spoken extensively about the relationship between light environment and steroidogenesis — the biochemical process by which your body manufactures hormones from cholesterol. When your light environment is disordered, your circadian rhythm is disordered. When your circadian rhythm is disordered, the hormonal cascade that drives testosterone production is blunted.
For us in Norway, this is particularly relevant. Mørketid runs from roughly October through February or March in most parts of the country. That is four to five months of light deprivation, and it is not just about mood or vitamin D. It is a systemic hormonal disruption that plays out quietly in the background while people wonder why they feel flat, tired, and less like themselves.
The 2016 University of Siena study is instructive here. Thirty-eight men with low sexual desire were split into two groups. One group received 30 minutes of bright light exposure (10,000 lux) each morning for two weeks. The other did not. The light therapy group saw testosterone levels rise from around 2.1 ng/ml to approximately 3.6 ng/ml — a 70% increase. Satisfaction scores improved. The control group saw no change. That is not a red light therapy study specifically, but it illustrates something important: light exposure, at the right time and in the right amount, is a direct hormonal signal. Not an indirect one. Not a placebo. A signal your endocrine system is actively listening for.
Where Red Light Comes In: The Leydig Cell Connection
Now here is where it gets genuinely interesting from a quantum biology perspective.
Your testes contain specialised cells called Leydig cells. They sit between the seminiferous tubules — the tubes where sperm are produced — and their job is to convert cholesterol into testosterone in response to luteinising hormone (LH) from the pituitary gland. Here is the critical detail: Leydig cells are exceptionally rich in mitochondria.
This is not a small detail. Steroid hormone synthesis — the entire process of making testosterone from cholesterol — is energy intensive. It requires a healthy supply of ATP. And mitochondria are the cellular machinery that produce ATP. So if your mitochondria are functioning well, your Leydig cells have the fuel they need to do their job. If your mitochondria are compromised, they may, as I have written about before, prioritise basic survival over specialised functions like hormone synthesis.
This is where red and near-infrared light (rødlysterapi / fotobiomodulasjon) becomes relevant.
The wavelengths we typically use in photobiomodulation — roughly 600nm to 900nm — are absorbed by chromophores within the mitochondrial membrane. At that interface, what researchers describe as a biological field-effect transistor, light reduces the viscosity of the interfacial water layers around ATP synthase, allowing the mitochondrial rotary motor to spin more freely and produce more ATP with less friction. You can think of it as clearing a blockage in a pipe that the mitochondria were trying to pump through.
More ATP available in the Leydig cells means those cells have more fuel to produce testosterone. The mechanism is not complicated once you understand the mitochondrial picture. It is also not magic — it is cellular energetics.
What the Animal Studies Actually Show
A 2013 study published in Biomedical Research by Ahn, Kim, and Rhee treated male rats with a 670nm diode laser and found a significant increase in serum testosterone levels without any visible histopathological side effects. The authors concluded that LLLT using 670nm might represent an alternative to conventional testosterone replacement therapy.
A 2020 study by Hasani and colleagues, published in Life Sciences, used photobiomodulation in mice with scrotal hyperthermia-induced testosterone suppression. The results showed significant restoration of sperm parameters, Leydig cell counts, and serum testosterone levels compared to untreated animals.
Both studies are animal studies. I am not pretending they are human clinical trials. They are not. But they do demonstrate the mechanism working in living testicular tissue, and that matters when we are assessing biological plausibility.
The 2024 systematic review published in Reproductive Sciences, which examined photobiomodulation across multiple wavelengths and sperm characteristics both in vitro and in vivo, concluded that results for sperm motility were genuinely promising — particularly in men with asthenozoospermia (low sperm motility). The authors noted that larger, better-controlled human trials are still needed for definitive clinical recommendations. That is honest science, and I respect it.
The Mitochondria Density Point Nobody Talks About
Here is something worth sitting with for a moment. Your sperm cells contain somewhere in the region of 50 to 75 mitochondria each, concentrated in the midpiece — the bit that powers the flagellum, the tail that drives the sperm forward. Sperm motility is therefore almost entirely a mitochondrial function. When researchers find that red light improves sperm motility, they are effectively demonstrating that photobiomodulation is reaching and improving mitochondrial function in exactly the reproductive tissues we are discussing.
That is not proof that it raises testosterone in humans. But it does tell you the light is penetrating testicular tissue, that the mechanism is active in reproductive cells, and that mitochondrial function in those tissues responds to red and near-infrared light.
For men who are in their 30s and 40s and noticing a gradual decline in energy, recovery, and drive — and wondering whether this is normal ageing or something more correctable — the mitochondrial picture is worth understanding. Dr. Doug Wallace's work on mitochondrial ageing makes a compelling case that much of what we call "normal ageing" is actually progressive mitochondrial decline. If testosterone synthesis is downstream of mitochondrial energy availability in Leydig cells, and if light can support mitochondrial function in those cells, the connection is at least mechanistically coherent.
Quantum Biology and Steroidogenesis
I want to go a little deeper here for those of you who are interested, because there is a layer to this that most of the testosterone content online completely ignores.
Dr. Fritz Albert Popp's work on biophotons — the coherent light emitted by living cells — raises an interesting question about whether the testicles might be involved in a broader photonic signalling network. Opsins, the photoreceptive proteins we normally associate with vision, have been found in testicular tissue, despite the fact that the testes are never exposed to sunlight directly. These are light-sensitive proteins sitting in tissues that receive no external light. What are they doing there?
The current hypothesis is that they respond to internally generated biophotons — the coherent light emitted by metabolically active cells — as part of a regulatory system. If that is the case, then external red light therapy might be interacting not just with the mitochondria directly but also with opsin-mediated signalling pathways in the testicular tissue.
This is genuinely emerging science. I am not presenting it as established fact. But it is the kind of thing that makes quantum biology so fascinating to dig into, because it suggests that light is playing a role in biological systems far beyond what mainstream medicine currently acknowledges.
The Norway Angle: Light Deficiency and Male Hormones
Here is the practical picture for us in Norway.
We are living through a period of profound light disruption. Most Norwegian men spend their working day under blue-dominant LED office lighting that suppresses melatonin and drives the circadian clock into a perpetual "midday signal" regardless of the actual time. Then they come home and watch a screen until midnight. Then they wonder why they do not feel like themselves.
Melatonin, as Dr. Russel Reiter's extensive research has shown, is not just a sleep hormone. It is a potent mitochondrial antioxidant. When melatonin production is suppressed by inappropriate light exposure, mitochondrial oxidative stress rises. When mitochondrial oxidative stress rises in Leydig cells, their capacity to produce testosterone declines. The chain is direct.
Red light in the morning supports circadian entrainment. Blue light blockers (blålysbriller) in the evening protect melatonin production. Both of these interventions are ultimately serving mitochondrial health, and through that, hormonal health.
I am not selling a testosterone supplement. I do not sell anything that will raise your testosterone levels in the way that a pharmaceutical intervention would. What I do sell is tools that support the light environment your biology actually evolved to operate in — and in Norway, especially from October through to late spring, that environment is severely compromised.
Whether you come to red light therapy for testosterone specifically, or for energy, recovery, skin, or simply because you find yourself flat and fatigued through mørketid, the mitochondrial pathway connects all of it. Your Leydig cells are not isolated from your general metabolic health. They are downstream of it.
What a Sensible Protocol Looks Like
I get asked about this directly, so I will address it plainly.
For general hormonal and mitochondrial support, a full body or half-body panel session of 10 to 20 minutes, 4 to 5 times per week, used at close range with bare skin, is a reasonable starting point. The wavelengths in the 600nm to 900nm range are the ones with the relevant research behind them.
Some people will additionally do targeted exposure to the inner thighs, lower abdomen, or lower back (for adrenal gland support — the adrenals produce a small percentage of testosterone). I have not seen convincing human data that this is dramatically more effective than general whole-body use, but the biological rationale is coherent.
The key variables are irradiance (the power of the light at skin surface), session length, and frequency. If you are using a low-powered device, sitting far away from the panel, or going through clothing, you are not getting the dose the research describes. If you want to know more about this, my FAQ page covers dosing in detail.
For those of you specifically interested in panels: our red light therapy panels include the multi-wavelength PulseWave range, which covers the relevant spectral ranges and includes a personal protocol document with purchase. If you want something portable for targeted use, the MEGA Torch delivers 810nm at intensities not available in any other handheld device in Norway.
References
Ahn JC, Kim YH, Rhee CK. The effects of low level laser therapy (LLLT) on the testis in elevating serum testosterone level in rats. Biomedical Research. 2013;24(1):28-32. Full text
Moradi A, Ghaffari Novin M, Bayat M. A Comprehensive Systematic Review of the Effects of Photobiomodulation Therapy in Different Light Wavelength Ranges on Sperm Cell Characteristics In Vitro and In Vivo. Reproductive Sciences. 2024;31(11):3275-3302. PubMed
Hasani A, et al. Photobiomodulation restores spermatogenesis in the transient scrotal hyperthermia-induced mice. Life Sciences. 2020;254:117767. PubMed
Pan R, Zhang G, Deng F, et al. Effects of red light on sleep and mood in healthy subjects and individuals with insomnia disorder. Frontiers in Psychiatry. 2023;14:1200350. PMC Full text
FAQ — Red Light Therapy and Testosterone
Can red light therapy increase testosterone in men? The animal evidence is encouraging, and the biological mechanism — red and near-infrared light stimulating mitochondrial ATP production in Leydig cells — is scientifically coherent. Human clinical trials are still limited and results are mixed. It is more accurate to say that red light therapy may support the hormonal environment rather than directly "boost" testosterone the way a pharmaceutical would. The indirect pathways — improved sleep, better circadian regulation, lower cortisol, reduced mitochondrial oxidative stress — are probably as important as any direct effect.
How does red light reach the Leydig cells? Near-infrared wavelengths in the 800nm to 900nm range penetrate several centimetres into tissue. Testicular tissue is relatively superficial. Studies investigating sperm motility after photobiomodulation have confirmed that light is functionally reaching reproductive tissues and improving mitochondrial activity there. Whether standing in front of a full-body panel delivers enough photons specifically to testicular tissue to produce a measurable hormonal effect in healthy human males is not yet clearly established.
Does the Norwegian mørketid affect testosterone levels? Almost certainly yes, though the research directly linking mørketid to testosterone is limited. We know that testosterone follows a circadian rhythm regulated by light exposure. We know that light deprivation disrupts circadian biology and, through melatonin suppression from indoor LED lighting, compromises mitochondrial function. We know from the University of Siena study that morning bright light exposure raised testosterone significantly in men with low sexual desire. Mørketid combined with indoor LED overexposure is essentially the opposite of that protocol.
How often should I use red light therapy for hormonal support? Most of the relevant research used sessions of 10 to 20 minutes, 4 to 5 times per week, at the relevant wavelengths. Daily use is not harmful. Consistency matters more than intensity. The broader mitochondrial and circadian benefits compound over time more than any single session.
Hva er sammenhengen mellom rødlysterapi og testosteron hos menn? Rød og nær-infrarød lys kan støtte produksjonen av adenosintrifosfat (ATP) i mitokondrier innenfor Leydig-celler i testiklene. Leydig-celler er de primære produksjonsenhetene for testosteron, og de er svært avhengige av energi fra mitokondrier for å syntetisere hormoner. Forskning på dyr viser økte testosteronnivåer etter behandling med rødlysterapi, men robuste kliniske studier på mennesker mangler fortsatt.
Bør jeg kombinere rødlysterapi med noe annet for hormonell støtte? Ja. Rødlysterapi er ikke et isolert tiltak. Den sterkeste effekten du sannsynligvis vil se, kommer fra å kombinere morgeneksponering for rødt lys (for sirkadisk regulering), blålysbriller om kvelden (for å beskytte melatoninproduksjonen), tilstrekkelig søvn, og reduksjon av kunstig lys om natten. Disse praksisene støtter alle mitokondriell helse, som er det biologiske grunnlaget for sunn hormonsyntese.
Disclaimer: This post is for informational and educational purposes only and does not constitute medical advice. If you have concerns about your hormone levels, please consult a qualified healthcare professional. The research referenced here represents emerging science and should not be interpreted as clinical recommendation.