Can red light therapy increase testosterone levels?
The research and personal accounts say yes. Men have experienced surges in libido and energy from sunbathing at the beach, or even mimicking these conditions with red light devices.
In particular, there are a few accounts of men increasing their testosterone levels with direct red light therapy to the gonadal area. (e.g. Greenfield, 2017)
Red light is the part of the light spectrum which is most protective. All light is useful, but red light in particular, stimulates energy production and biological processes at a very deep level.
While it has been found to be very effective and therapeutic for various conditions and illnesses, the research isn’t as abundant for the specific perspective of increasing serum androgen levels (e.g. testosterone), at least in humans.
As usual, however, there is interesting evidence from animal (mice) models. A study by Hasani et al. (2020) found a positive effect of photobiomodulation (red light therapy) on the serum testosterone levels in mice:
“Our outputs indicated that PBM could largely improve the sperms parameters and stereological parameters, like spermatogonia, primary spermatocyte, round spermatid and Leydig cells together with an increasing level of the serum testosterone and GSH activity compared to the scrotal hyperthermia induced mice.”Hasani et al. (2020)
This finding corroborates an earlier study by Ahn et al. (2013), which obtained analogous results in an experiment involving rats:
“Thus the LLLT using a 670-nm diode laser was effective in increasing serum T level without causing any visible histopathological side effects. In conclusion, the LLLT might be an alternative treatment modality to the conventional types of testosterone replacement therapy.”Ahn et al. (2013)
In both studies, the experiment involved using red light devices to stimulate testosterone production. The study by Ahn et al. (2013) in particular points out the effectiveness of the very common 670nm wavelength* light frequency in increasing serum testosterone levels, when compared to another group exposed to 808nm wavelength. (* 670nm is in the deep-red range of the light spectrum, while 808nm is in the infrared region.)
It is important to recognize that red light is probably not exclusively responsible for health benefits of light exposure. Other parts of the light spectrum, including the UV (ultraviolet) range from 200-400nm have also been shown to stimulate androgen production. A study by Myerson (1939) showed that exposure of the genital area to UV light greatly stimulated androsterone production in men.
The obvious problem with UV light is that it contributes to skin aging (Rittié & Fisher, 2002), but this reinforces the importance of sun exposure (which provides a natural balance of ultraviolet and red light). Sunshine remains the optimal way to stimulate production of the protective hormones, as it also increases vitamin D, which in itself improves serum testosterone levels. (Wehr, 2010)
That being said, the evidence seems to indicate that red light devices offer a quick and easy way to raise testosterone levels (as well as other protective hormones, in all likelihood). Moreover, deep red light emits very little heat, and is therefore safe for the sensitive genital area, since the testicles are sensitive to excess warmth. (Alves, 2016)
With regards to sexual function and libido, exposure to bright light seems to increase testosterone levels, as well as sexual function and satisfaction. (ECNP, 2016) Furthermore, red light devices have been shown to increase sperm quality (Gabel et al., 2018; Safian et al., 2020; Hasani et al., 2020). For the interested reader, Zupin et al. (2020) constitutes an excellent review of the effects of red light therapy for male fertility.
To conclude, red light therapy in the deep-red wavelength range (650nm-700nm), applied relatively close (6-12″) to the genital area, can probably increase testosterone levels. In all likelihoods this is the optimal light frequency, as higher (infrared) wavelengths may emit more heat than is necessary and this could be harmful to the testicles. This type of therapy can supplement an effort to get more sunshine exposure in general, while also compensating for a deficiency of light in one’s environment.
Wehr, E et al. “Association of vitamin D status with serum androgen levels in men.” Clinical endocrinology vol. 73,2 (2010): 243-8. doi:10.1111/j.1365-2265.2009.03777.xhttps://pubmed.ncbi.nlm.nih.gov/20050857/
Myerson, A. Influence of ultraviolet radiation on excretion of sex hormones in the male. Endocrinology 1939;25:7-12.
Ahn et al. The effects of low level laster therapy (LLLT) on the testis in elevating serum testosterone level in rats. Biomedical Research 2013; 24(1): 28-32 https://www.alliedacademies.org/articles/the-effects-of-low-level-laser-therapy-lllt-on-the-testis-in-elevatingserum-testosterone-level-in-rats.pdf
Hasani, Amirhosein et al. “Photobiomodulation restores spermatogenesis in the transient scrotal hyperthermia-induced mice.”Life sciences vol. 254 (2020): 117767. doi:10.1016/j.lfs.2020.117767https://pubmed.ncbi.nlm.nih.gov/32407848/
Alves, Maíra Bianchi Rodrigues et al. “Low-level laser therapy to recovery testicular degeneration in rams: effects on seminal characteristics, scrotal temperature, plasma testosterone concentration, and testes histopathology.” Lasers in medical science vol. 31,4 (2016): 695-704. doi:10.1007/s10103-016-1911-1https://pubmed.ncbi.nlm.nih.gov/26914685/
Gabel, C Philip et al. “Sperm motility is enhanced by Low Level Laser and Light Emitting Diode photobiomodulation with a dose-dependent response and differential effects in fresh and frozen samples.” Laser therapy vol. 27,2 (2018): 131-136. doi:10.5978/islsm.18-OR-13https://pubmed.ncbi.nlm.nih.gov/30087533/
Zupin, Luisa et al. “Photobiomodulation therapy for male infertility.” Lasers in medical science vol. 35,8 (2020): 1671-1680. doi:10.1007/s10103-020-03042-x https://pubmed.ncbi.nlm.nih.gov/32483749/
Safian, Fereshteh et al. “Photobiomodulation with 810 nm Wavelengths Improves Human Sperms” Motility and Viability In Vitro.” Photobiomodulation, photomedicine, and laser surgery vol. 38,4 (2020): 222-231. doi:10.1089/photob.2019.4773 https://pubmed.ncbi.nlm.nih.gov/32301671/
Rittié, Laure, and Gary J Fisher. “UV-light-induced signal cascades and skin aging.”Ageing research reviews vol. 1,4 (2002): 705-20. doi:10.1016/s1568-1637(02)00024-7 https://pubmed.ncbi.nlm.nih.gov/12208239/
European College of Neuropsychopharmacology (ECNP). “Lack of interest in sex successfully treated by exposure to bright light.” ScienceDaily. ScienceDaily, 18 September 2016. www.sciencedaily.com/releases/2016/09/160918214443.htm
BBC News, Sunbathing ups men’s testosterone. Feb 2010, http://news.bbc.co.uk/2/hi/health/8493042.stm
Ben Greenfield (2017). https://www.menshealth.com/health/a19539973/i-put-a-giant-red-light-on-my-balls-to-triple-my-testosterone-levels/