Chang's eBooks study was done in 2010, after f.lux shipped but before we figured out who to talk to about it.
If you want to see fluence-response curves for single-wavelength lights, this is a really neat reference:
http://www.cet.org/wp-content/uploads/2014/06/Gooley-2010-Sc... - this one makes the case for some cone interactions when people are sensitized to darkness.