• Blue light suppresses the release of endogenous melatonin. To get an idea of how much it suppresses, it, take a look at the image below. In this image participants were exposed to no light, or a 2 lux light at 460nm (blue line) or 560nm (green line) for 1.5h. source

      As for the mental stimulation part, that’s going to vary a lot more from person to person and how engaging the content is, but you’re right that being mentally stimulated in the wrong ways can keep you awake too.

    • Blue light has a documented effect on our circadian rhythm and melatonin production. It’s been studied quite a bit. I’m sure mental overstimulation is a component, but it absolutely is not the whole story.

      In Western society, there is a big focus on silver bullet solutions because people don’t want to address issues in a holistic way. Thus, you have blue light filters instead of turning the screen off.