I'm concerned that the upper layer of the cortex is getting too much of the light. Looking at the graph below, it appears reasonable that there will be situations where 2% of the light energy will be blocked by the upper 1 mm layer of the cortex (if 3% makes it through skull and 1% is remaining after 1 mm of cortex depth). Given that my device is capable of supplying 0.1 W/cm^2, 2% will be 0.002 W into a volume of cortex that is 0.1x1x1 cm^3 = 0.1 cm^3, or 0.02 W/cm^2. A human is about 60,000 cm^3 and burns about 100 W, which is 0.0016 W/cm^3, so my device has been heating the upper neurons of my cortex 10 times more than my body heat which does not sound good at all. However, we can withstand over 30 mW/cm^2 for 4 hours a day from the Sun, so 100 mW/cm^2 must not be very dangerous. The blood circulation certainly must have the ability to carry the heat away. If the full body gains 10 F, then this ability is lost and death is imminent. 0.02 W/cm^3 would raise the water-like cortex 2 C in 100 seconds if the heat were not carried away. Ultrasound which goes about 5 times deeper (5 cm) than light therapy and a safety limit is said to be 500 mW/cm^2 when applied to the brain. Ultrasound has been used to improve mood. They also said electrical stimulation improved memory. Ultrasound can be used as high as 1 W/cm^2 for the hip and I've very successfully used probably over 2 W/cm^2 light therapy with a 75 W halogen and water-filled snow globe for a broken pinkie toe.
