Application of Light: Location and Penetration

The researchers discuss three methods for applying light to the brain: using light on circulation-rich zones (axillary area, wrist, groin) to have downstream effects on memory disorders, utilizing light therapy on bones to mobilize stem cells, and delivering light through the skull (occiput) to reach the brain. They mention the optical tissue window that allows wavelengths of light between 650 and 1200 nanometers to penetrate through skin and skull. The researchers recommend using an 800 to 810 nanometer wavelength for penetration through the skull and a 970 to 1064 nanometer wavelength for deeper penetration into brain tissues.