2026 ECNP Congress

PS03-3254

Light therapy in primary and secondary sexual disfunctions

Veronica Milani — L. Bossini, S. Pardossi, M.B. Rescalli, M. Kousoula, F. Castaldo, A. Santangelo, F. Torrigiani, G. Marino, A. Francomano, C. Pierini, M. Pinzi, A. Fagiolini · Università di Siena, Medicina Molecolare e dello Sviluppo, Siena, Italy

2026 ECNP Congress

Background

Sexual dysfunctions may occur in psychiatric patients either as primary conditions or secondary to psychopharmacological treatments such as selective serotonin reuptake inhibitors (SSRIs), significantly impacting both sexual functioning and affective symptoms [1,2]. Given the established efficacy of light therapy on affective symptomatology and ist potential effects on sexual functioning [3], this study aims to evaluate ist efficacy in primary sexual dysfunctions (according to DSM-5 criteria) and SSRI-induced sexual dysfunction[4]. Additionally, plasma testosterone and sex hormone-binding globulin (SHBG) levels were monitored due to their role in sexual function [5].

Methods

This prospective interventional study enrolled seventeen male participants with primary sexual dysfunction or dysfunction secondary to psychopharmacological treatment, diagnosed using the Structured Clinical Interview for DSM disorders screening version (SCID-S). Participants completed a fifteen day course of morning light therapy, consisting of thirty minutes per day of exposure to a white fluorescent light box with an ultraviolet filter, delivering 10000 lux at 30 cm from screen to cornea. The sessions occurred immediately after awakening, between 7:00 and 8:00 a.m. Serum total testosterone and sex hormone binding globulin were measured at baseline and post treatment. Sexual and affective outcomes were assessed using the Arizona Sexual Experience Scale (ASEX), the Changes in Sexual Functioning Questionnaire short form (CSFQ-14), and the Hamilton Depression Rating Scale (HAM-D). Adverse events were monitored. No serious adverse effects or protocol deviations were reported during the intervention period. Patients with hormonal, endocrine, metabolic, or urological disorders were excluded. Statistical analysis was performed using a paired t-test to compare baseline and post-treatment measures.

Results

Patients with primary sexual dysfunction (n = 7) showed greater improvement in sexual functioning (ASEX Δ−3.86; CSFQ-14 Δ+4.29), associated with a reduction in affective symptoms (HAM-D Δ−6.29), without significant changes in testosterone (Δ−0.12) and with a slight increase in SHBG (Δ+0.97). Between-group comparison showed statistical significance for CSFQ-14 (p ≈ 0.02) and a trend toward significance for ASEX (p ≈ 0.05).In contrast, patients with secondary sexual dysfunction (n = 10) exhibited a smaller improvement in sexual function (ASEX Δ−1.60; CSFQ-14 Δ−0.20), but a greater reduction in affective symptoms (HAM-D Δ−3.80), with stable testosterone levels (Δ−0.04) and a more pronounced increase in SHBG (Δ+3.00). Between-group comparison was significant for HAM-D (p ≈ 0.04), but not for hormonal parameters.

Conclusions

The findings suggest that light therapy is associated with a marked improvement in sexual functioning in patients with primary sexual dysfunction, likely related to circadian dysregulation and reduced libido, in the absence of significant changes in total testosterone and SHBG levels. From a study expansion perspective, the inclusion of free testosterone assessment, in addition to total testosterone and SHBG, may allow a more accurate evaluation of androgen bioavailability and its potential modulatory role in the clinical response to light therapy.

References

  1. :Bossini L., Fortini V., Casolaro I., Caterini C., Koukouna D., Cecchini F., Benbow, J., & Fagiolini, A. (2014).Sexual dysfunctions, psychiatric diseases and quality of life: A review. Psychiatria Polska, 48(4), 715-726.
  2. : Bossini L., Fagiolini A., Valdagno M., Roggi M., Tallis V., Trovarelli S., Ponchietti R., Castrogiovanni P. Light therapy as a treatment for sexual dysfunctions.Psychotherapy and Psychosomatics. 2009;78(2):127–128
  3. : Pardossi S., Bossini L., Milani V., Rescalli M.B., Cuomo A. Bright Light therapy in Psychiatric disorders: Mechanisms, Clinical procedure and evidence.Life, 2026; 16(3):449.
  4. : Bossini L., Caterini C., Koukouna D., Casolaro I., Roggi M., Di Volo S., Fargnoli F., Ponchietti R., Benbow J., Fagiolini A.Light therapy as a treatment for sexual dysfunctions. Beyond a pilot study.Psychiatria Polska. 2013;47(6):1113–1122.
  5. : Koukouna D., Bossini L., Casolaro I., Caterini C., Fagiolini A.Light therapy as a treatment for sexual dysfunction; focus on testosterone levels.European Neuropsychopharmacology. 2016;26(Suppl 2):S606