Fig. 1

Phototherapy and the underlying mechanisms. a Introduction of light. The electromagnetic spectrum illustrates the distribution of electromagnetic waves across various wavelengths. The enlarged section corresponds to the ultraviolet, visible, and infrared regions, which are the primary wavelengths used in phototherapy applications. b Schematic representation of the main mechanisms involved in phototherapy, including optogenetics²⁴, photobiomodulation²⁷, photodynamic therapy³⁰, and blue light therapy¹³. Optogenetics activates light-sensitive proteins, such as channelrhodopsin-2 (ChR2), allowing significant cation influx, particularly Na⁺, through ion channels, leading to depolarization and neuronal excitation. Photobiomodulation employs red and near infrared (NIR) light to activate cytochrome C oxidase (CCO) in the mitochondrial electron transport chain, enhancing ATP synthesis and reducing oxidative stress while upregulating signaling molecules such as nitric oxide (NO) and calcium ions (Ca²⁺). ATP, adenosine triphosphate. Photodynamic therapy uses light of specific wavelengths to activate photosensitizers (PSs), generating reactive oxygen species (•OH, •O₂^-, and ¹O₂) to eliminate cancers and pathogens. Blue light phototherapy enhances bilirubin absorption in the skin, converting it into water-soluble lumirubin, which is excreted from the body without hepatic metabolism. c Representative applications of diseases treated with phototherapy and their corresponding research references: encephalopathy^25,49,50,51, ophthalmopathy³⁷, anti-cancer^{58,150,165,166,167}, neonatal jaundice¹³, spinal-cord injury⁵², peripheral nerve modulation^53,54, thrombocytopenia¹⁶⁸, hair loss¹⁸, cosmetic dermatology³¹, anti-bacterial^7,169,170, heart disease^19,41,42, diabetes^{43,44,45,46,47}, bladder pain syndrome⁴⁸, wound healing^17,34, and diabetic foot ulcer^35,36. Figure 1, created with BioRender.com, released under a Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International license