Is there a reason Germania aircraft cabins have blue lights? On my 2014-01-18 CET flight ST2114 from FKB to LPA on a Germania airplane, cabin lights were switched from white to blue for takeoff. I recorded this in a panoramic photo.

Granted, on sunset, the sun coming in through the windows made up for a beautiful play of light: Blue and yellow are complementary colors.

Is there a security or technical reason for the blue light, or is it just for
aesthetics?
Bergische Universität Wuppertal has done some research that chronobiologically-adapted LED lighting can enhance passengers well being and they can sleep better during a flight.

This article details about this research:


  Adaptive solid-state lighting (SSL) scenarios in which the color and
  brightness of lighting is varied during long-distance overnight
  flights results in passengers that sleep better and are more alert
  upon arrival.
  
  ... at the start of an overnight flight that warm-white light helps to
  stimulate melatonin production and increases passenger relaxation ...
  blue-rich cold light in the morning increased alertness


There have been studies showing benefits of biologically effective lighting for more relaxed flights.