From a purely biological perspective, testosterone is generally responsible for many of the qualities considered “manly”—deeper voices, hairy chests, muscular frames, etc. That’s why men produce far more testosterone than women.
Unfortunately, around age 30, testosterone levels start to drop. This is normal, but that doesn’t make it easy to deal with. Waning testosterone levels can bring a lot of challenges to a man’s life—things like lower energy, reduced sexual drive & performance, a decline in muscle, as well as weight gain. 
To make matters worse, testosterone is adversely affected by a host of common challenges that affect nearly all modern men, like nutrition, stress, and lack of sleep—to name just a few. These factors combine to produce dramatically decreased testosterone levels for a lot of men.
Doctors often suggest supplementation or medication to help with the difficulties of low testosterone or to treat testosterone abnormalities. But these conventional solutions lead to unwanted side effects for many patients. So it’s no surprise that a lot of men want a more natural option to boost their testosterone, and with it their energy, sex drive, and physical performance. One promising option is light therapy, as recent medical studies are demonstrating its immense potential for increasing male testosterone. This has been repeatedly proven in clinical trials on various mammals in the past few decades, but recent studies on human men are giving researchers and endocrinologists even more reasons for optimism.
Clinical Research Shows Light Therapy’s Potential for Increasing Testosterone
Medical scientists have been studying the effects of natural light on testosterone production for almost a century. Research over the last decade, and especially the last few years, has been even more illuminating and given the medical community more concrete reasons to believe in light therapy’s potential for increasing male testosterone.
Italian Pilot Study: A 2016 randomized, placebo-controlled pilot study conducted by the University of Siena in Italy evaluated 38 men with a diagnosed low sexual desire. Researchers measured their testosterone levels and separated the men into two groups, with one group receiving a clinical dose of light therapy in the early mornings. In addition to higher sexual satisfaction, the men in the group treated with more light saw their T-levels rise significantly. The control group did not see testosterone rises, but the active light therapy group showed a huge increase from about 2.1 ng/ml to 3.6 ng/ml in just 2 weeks. 
Dr. Andrea Fagiolini, the study’s lead researcher, explained the findings: “The increased levels of testosterone explain the greater reported sexual satisfaction. In the Northern hemisphere, the body’s testosterone production naturally declines from November through April, and then rises steadily through the spring and summer with a peak in October. You see the effect of this in reproductive rates, with the month of June showing the highest rate of conception. The use of the [light therapy device] really mimics what nature does.” 
Male Fertility: Numerous other studies over the last 5 years have found that increased natural light exposure to a man’s testes and sperm actually increases sperm motility, or how well individual spermatozoa are able to move and swim. Motility is a key measure of male fertility and reproductive health. As a result, many researchers are concluding that light therapy can have a significant effect on treating male infertility. [4,5,6,7]
In addition to noting increased sperm motility, a 2017 study published in Scientific Reports found that these treatments were safe, and did not induce any oxidative DNA damage to the sperm or testes. 
Ben Greenfield (The world-famous trainer & biohacker), Mike Mutzel, aka Metabolic Mike, (another top trainer) and UFC Champion TJ Dillashaw (still holds the UFC bantamweight championship) have all tried red light therapy and realised how beneficial it has been for them.
NFL stars like Patrick Peterson from The Arizona Cardinals incorporates the red light therapy in his training and states his energy is way up.
A 2013 study of light therapy treatments conducted by Harvard and MIT researchers praised its “non-invasive nature and almost complete absence of side effects.” 
Conclusion: Light Therapy Could be a Game-Changer for Boosting Natural Male Testosterone
Emerging research on light therapy and its effect on male testosterone, fertility, and sex drive is extremely encouraging. Taken together with previous lab research, and the current experiences of top athletes and trainers using this therapy, it’s clear that light therapy has the potential to be a game-changer for men who are looking for an increase in natural testosterone production.
With thanks to the JOOV laser website.
Scientific Sources and Medical References:
 Fagiolini A et al. Lack of interest in sex successfully treated by exposure to bright light. European College of Neuropsychopharmacology. Sept 2016. European College of Neuropsychopharmacology (ECNP). “Lack of interest in sex successfully treated by exposure to bright light.” ScienceDaily. ScienceDaily, 18 September 2016.  Vladimirovich Moskvin S., Ivanovich Apolikhin O. Effectiveness of low level laser therapy for treating male infertility. Biomedicine (Taipei). 2018 June; 8(2):7.  Ban Frangez H., Frangez I., Verdenik I., Jansa V., Virant Klun I. Photobiomodulation with light-emitting diodes improves sperm motility in men with asthenozoospermia. Laser in Medical Science, 2015 Jan;30(1):235-40. Salman Yazdi, R., Bakhshi, S., Jannat Alipoor, F. et al. Effect of 830-nm diode laser irradiation on human sperm motility. Lasers Med Sci. (2014) 29: 97.  Chow KW, Preece D, Burns MW. Effect of red light on optically trapped spermatozoa. Biomedical Optics Express. (2017) Aug 23;8(9):4200-4205. Preece D., Chow KW, Gomez-Godinez V., Gustafson K., et al. Red light improves spermatozoa motility and does not induce oxidative DNA damage. Scientific Reports. 2017 Apr 20;7:46480. Avci P, Gupta A, et al. “Low-level laser (light) therapy (LLLT) in skin: stimulating, healing, restoring.” Seminars in Cutaneous Medicine and Surgery. Mar 2013; 32(1): 41-52.
 Healthline, Gotter A and Rogers G, MD. Low Testosterone in Men. Healthline. Jul 2016.