In Small Study, High Intensity Light Therapy Boosts Libido in Men
The same type of high-intensity light therapy used to treat seasonal affective disorder (SAD) and as an adjunctive treatment for non-seasonal depression has been found to boost testosterone and improve sexual satisfaction in men with low libido.
In a study by Andrea Fagiolini and colleagues, men with low sexual desire or trouble getting aroused were exposed to the high intensity light (10,000 Lux) for a half hour upon waking. Compared to men who used a lightbox that filtered the light to only 100 Lux, men exposed to the high-intensity light for two weeks showed increased testosterone in the blood and reported greater sexual satisfaction. Testosterone levels increased from around 2.1 ng/ml to 3.6 ng/ml in the high-intensity light group. (There were no significant changes in the comparison group.) Light therapy is quite safe for people without eye problems.
Fagiolini explained that in the Northern hemisphere, testosterone production declines from November to April and then rises again through the spring and summer, peaking in October. He suggests that the light therapy mimics the effect of summer light on the body, perhaps by inhibiting the pineal gland, which secretes hormones.
Fagiolini and colleagues hope to replicate the study with a greater number of participants and to determine how long the results may last.The study of 38 participants was presented at the 29th Congress of the European College of Neuropsychopharmacology in 2016.
Light Therapy Effectively Treats Non-Seasonal Depression
Doctors have known for some time that treatment with high-intensity light (7,000–10,000 Lux) can improve seasonal depression. In an 8-week study published in the journal JAMA Psychiatry in 2015, researcher Raymond Lam compared four different treatment options for non-seasonal major unipolar depression: bright light therapy for 30 minutes per day first thing in the morning, 20 mg of the antidepressant fluoxetine per day, combined bright light therapy and fluoxetine, and a placebo device paired with a placebo pill.
The combination of bright light therapy and fluoxetine produced remission in 58.6% of the participants who received it, compared to remission rates of 43.8% for bright light alone, 19.4% for fluoxetine alone, and 30% for placebo. It is notable that the effects of fluoxetine did not exceed those of placebo, but the effects of light alone did. There were few side effects in any group.
These data provide convincing evidence of the efficacy of light therapy in the treatment of non-seasonal unipolar depression. Use of light therapy for non-seasonal depression should now be more routinely considered, particularly when combined with antidepressant treatment.
Patients who had previously failed to respond to two or more antidepressants and patients with bipolar depression were excluded from the study. Bright light therapy administered in the morning can sometimes bring about mixed states in people with bipolar disorder. A 2007 case study by D. Sit and colleagues in the journal Bipolar Disorders found that midday light led to more improvement and less risk of mixed states than morning light among women with bipolar disorder.
