156669 20251017144609.0 doi 10.3390/life15050715 sideral 143937 ART-2025-143937 eng Sanchez-Cano, Ana Universidad de Zaragoza (orcid)0000-0002-5621-1937 Comparative Effects of Red and Blue LED Light on Melatonin Levels During Three-Hour Exposure in Healthy Adults 2025 Access copy available to the general public Unrestricted Circadian rhythms, essential for regulating human physiology and behavior, are influenced by light exposure, particularly at night. This study examined the impact of red (631 nm) and blue (464 nm) LED light on melatonin secretion, a key circadian marker. Twelve participants aged 19–55 years were exposed to red and blue light for three hours (9:00 p.m.–midnight), with hourly saliva samples analyzed via ELISA to track melatonin levels. Initially, melatonin levels were comparable under both light conditions. After one hour, both lights suppressed melatonin, but differences emerged after two hours: blue light-maintained suppression, with levels at 7.5 pg/mL, while red light allowed recovery to 26.0 pg/mL (p = 0.019). This pattern persisted at the third hour. Blue light had stronger suppression effects, particularly in younger participants and men. These results underscore blue light’s disruptive effects on circadian health and highlight red light as a less disruptive alternative for nighttime environments. info:eu-repo/grantAgreement/ES/DGA/LMP39_21 info:eu-repo/grantAgreement/ES/UZ/JIUZ-2021-CIE-03 info:eu-repo/semantics/openAccess by https://creativecommons.org/licenses/by/4.0/deed.es info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Luesma-Bartolomé, María José Universidad de Zaragoza (orcid)0000-0003-4071-1467 Solanas, Estela Universidad de Zaragoza (orcid)0000-0001-8056-5236 Orduna-Hospital, Elvira Universidad de Zaragoza (orcid)0000-0003-2710-1875 1003 027 Universidad de Zaragoza Dpto. Anatom.Histolog.Humanas Area Anatom.Embriol.Humana 2002 647 Universidad de Zaragoza Dpto. Física Aplicada Área Óptica 15, 5 (2025), 715 [15 pp.] Life (Basel) Life 2075-1729 1782239 http://zaguan.unizar.es/record/156669/files/texto_completo.pdf Versión publicada 2584406 http://zaguan.unizar.es/record/156669/files/texto_completo.jpg?subformat=icon icon Versión publicada oai:zaguan.unizar.es:156669 articulos driver 2025-10-17-14:16:22 ARTICLE