[jimtorr]

What could be the link between blue light and an internal organ? Why only at night?

Sounds like another government grant to me.

[BlueLancer]

What could be the link between blue light and an internal organ? Why only at night?

Well, I'm sure that you've heard the old adage: "They're blowing smoke up your @$$"?

This is the updated version: "They're shining a blue light up your @$$"...

[T-Bone Texan]

I posit the true link is that people who work nigh shifts tend to smoke more and engage in other behaviors that others do not, like drinking vodka straight from the bottle.