> The problem is that we keep our brains active late at night and that's the reason why it is hard to get to sleep. You are correct, however, that's a confound

> The problem is that we keep our brains active late at night and that's the reason why it is hard to get to sleep. You are correct, however, that's a confounding problem. The (relatively) weak effectiveness of software solutions is due to blocking only a small percentage of blue light from a (relatively) strong light source (assumes short distance to screen, low ambient light at night). Blue light (and even some green light frequencies) is a hardwired stimulus feeding into your circadian rhythm. Blocking all blue and green frequencies, e.g. with simple welding glasses, is effective in supporting the creation of melatonin. But again, having enough melatonin in your system is a necessary but not sufficient condition to be able to sleep.