PhotonWrangler
Flashaholic
I ran across this article about a study where they had test subjects of varying ages stare into a red LED for a few minutes in the morning. The article claims that this stimulated mitochondria in the eyes and resulted in improvement in color perception in subjects over 40. The study also had their subjects try this at mid-day and evening and found that there was little to no improvement in vision when done at these times as the eyes had already adapted to daylight and thus minimized the benefit.
They used ordinary red 670nm LED flashlights in the study. Here's a photo of one of their lights.
They used ordinary red 670nm LED flashlights in the study. Here's a photo of one of their lights.