There must have been some hypothesis or they wouldn't have studied the result. Probably got lost in translation. EDIT: When an english speaking reporter can't

There must have been some hypothesis or they wouldn't have studied the result. Probably got lost in translation. EDIT: When an english speaking reporter can't figure something out in a foreign country they often say "nobody knows ..." but really they mean "I couldn't find a source to tell me ..." EDIT 2: I'm sorry, I didn't realize this was discussed in the movie. I just got to that part. Clearly the author of the film knows plenty of Japanese people and knows this subject well. At the same time there was still a scientific reason for installing them: other posters are pointing out that there have been studies measuring blue light showing it is a "stimulus for acute melatonin suppression" . Interesting!