I find when I don't use my phone for hours before bed I get a lot better sleep. That is confirmed by the study you found about lesser levels of melatonin being produced by the blue light. Another thing that may cause breast or prostate cancer is the radiation from phone! Having it in your pocket all day can emit radiation to guy's groins, and girls put their phones in between their breasts (think sport's bra). This is an interesting study, and I'm glad you revealed it. Correlation does not always imply causation though.