I'm a bit skeptical of many of the claims that paper or e-ink in the evening has less effect on circadian rhythms than a normal screen does. What would be the mechanism for this?

One claim I've seen is that it is because they are frontlit rather than backlit. But to the photosensor cells that sense the light and report to the parts of the brain that control circadian rhythms, it should just be frequency and intensity that matters. Light of a given frequency and intensity should have the same effect regardless of whether it came from a frontlit or a backlit display.

I have noticed that the brightness I need to comfortably read a normal screen seems to be higher than the brightness I need to comfortably read paper. Perhaps that is the difference--we simply use less light with paper?

Or perhaps with paper, where we get to choose what light to use for our nighttime reading, and it is often done with a light dedicated specifically to that task, we tend to choose low blue lights?

> Or perhaps with paper, where we get to choose what light to use for our nighttime reading, and it is often done with a light dedicated specifically to that task, we tend to choose low blue lights?

An e-ink screen with light turned off should be similar to paper (a little less contrast than a book, perhaps, but higher than a "grey" newspaper).

And while we have a lot of terrible modern light sources, a regular glow lamp would be much warmer than a typical "white" led.

All I can say is if I read from my iPad or iPhone in bed, it can keep me up nearly indefinitely. If I read in my e-ink Kindle with a front light, I will get so sleepy so fast I can only get through a few pages each night.

I always switch my ereader to black background and yellow font during the day. At night I have an orange font if it's really dark, but usually I just dim the yellow font.

I hate reading black font on a white background, too bright.

Thank you for the advice. I am using app that blocks blue light(1) ( I am sure many people use it and it is famous already). Also great thing about using a phone is that of great apps that allow to listen to your books where you left off (2), also it has in-built dictionary for faster reading. And the speed reading apps (3). I don't think reading is any different from researching where you use a laptop to read research papaers.

1. Twilight, f.lux you name it. 2. (android only) https://play.google.com/store/apps/details?id=com.prestigio.... - very great app, you can use widget to see your library also. You can use any TTS ( I use Google) to listen to the book.

3. https://play.google.com/store/apps/details?id=azagroup.reedy

You can set speed, pause easily. A great app that is used for deliberate practicing speed reading skill. Increasing the WPM to an uncomfortable level. Also you can read before bed without having to turn next page.