I swap metaphor + analogy frequently, along with model, schema,
   etc tongue emoticon I didn't pick the blue light sensor at
   random - it's from research I've done through the years on SAD,
   as well as the body's clock, etc. I have a nice drawing
   somewhere that shows the awakening process (when it's the
   regular sleep/wake cycle anyway) and the involvement of the the
   blue light sensor. I used to know the frequency number of it by
   heart too - I forgot what it was. But I found it fascinating
   because I suspect it also might be part of the reason for
   blindsight and that someone who is entirely blind from birth yet
   retains that sensor whose name I forget - might have it better
   synchronized with the motor/directional/hearing systems to allow
   fast reaction times as, say, when a blind person can catch a
   ball coming at them. Never seemed too strange to me because I
   can navigate pretty well in pitch black. so I suspect mine is
   kinda strong, but I dunno.