Long-wavelength light, including red light, has a positive effect on blood glucose levels and mitochondria.

“Long-Wavelength Light & Blood Glucose; Mitochondria 36:19”

“he found that those that were exposed to red light and didn't know it had lower glucose concentrations so he surmised that the mitochondria were working more efficiently they were using up more energy and this is the reason why the glucose didn't Peak as high”