Lights on for the Nervous System: Exploring the Effects of Photobiomodulation, Part A, Volume 187 in the International Review of Neurobiology series, highlights new advances in understanding how light interacts with the human body and brain. This comprehensive volume presents chapters written by international authors, covering the history and theory of therapeutic light use, underlying mechanisms of light-cell interactions, and the systemic effects of light exposure. Chapters explore the History of Humans Using Light, Theory of Light: Why Should It Work, Mechanisms of Light, Systemic Effects of Light, Light Application and Dosage, How Does Light Affect Brain Activity, and much more. Additional sections cover Light Talks: The Role of Biophoton in Cellular Communication, Biophotons: Communication with Light, Light Effects on Brain Activity: Simulations/Dynamic Function, Cognitive Enhancement through Transcranial Infrared Laser Stimulation: Insights from Research, Light Effects on the Microbiome, Lights On for Sleep, Exploring the Effect of Red and Near Infrared Light on Neurodegenerative Disease, Light Effects on Parkinson's Disease: Intracranial Application, Light Effects on Parkinson's Disease: Transcranial Application, Lights On for Chronic Pain, Light Effects on Chronic Traumatic Encephalopathy and TBI, Light Effects on Traumatic Brain Injury, Light Effects on Depression, Light Effects on Retinal Disease, and Does Light Change the Inner Workings?.