The bases for this therapy is not topical (Exposure to the skin), it has to do with the ability of this wavelength of light to penetrate through the skin and have an effect on your circulating white cells, specifically T-Cells. The amount of cells affected is based on area treated/exposed to the light, penetration of the light (intensity) and blood flow through the area. The latter would be higher in a warmer climate. Intensity, Area, Duration and Frequency of treatment all would influence the volume of white cells affected. I do not believe that a flashlight with different LEDs would provide the area nor the penetration (output/lumens) that seems to be needed for this form of therapy, so to give it a reasonable chance of seeing an affect I would try to replicate the conditions used in the medical studies. I have spent 30 years conducting medical trials, and still do some consulting in biotech. Have seen a lot of different medical therapies, some work, most do not. I just believe you need to try to replicate the actual treatment conditions, and have some means to evaluate the response. Spending $40 on a bulb may be reasonable when you consider the cost of other treatments. Work with your local doctor.