I believe that it is the intensity rather than the colour temperature of light that keeps you awake at night. The reason that red shifting the light works is th

I believe that it is the intensity rather than the colour temperature of light that keeps you awake at night. The reason that red shifting the light works is that our eyes are more sensitive to the greener part of the spectrum (shifting towards red) and therefore you need a lot more blue light to see the same detail as you would for green or red light. If you have an e-reader that only emits bluish light like a kindle paperwhite then you can turn down the light intensity and increase the font size to compensate for lost of detail sensitivity.