What strikes me with fear is that the cabin crew can over ride the passeneger switch and set all to close. So on a daytime flight back form the Far East you may be in total darkness whilst outside the sun is shining.

OK, time to put the cat amongst the pigeons. Personal choice is the over-riding factor and not the Big Brother approach. Passengers and not crew should have the right to decide when shutters go up or down so definitely not in favour of being dictated to. If other passengers wish to sleep simply provide them with eye-shades and let them get on with it.