My obsession with eyestrain started in junior high. Within a year of getting my first laptop, I had to be fitted for my first pair of glasses. From then on I did everything I could to keep my eyes from getting worse. Originally that meant turning my monitor brightness way down and taking frequent breaks from the screen. But in the years since, as research pours in showing that our constant exposure to artificial light may lead to everything from insomnia to obesity to prostate cancer, I've had to up my vigilance.