Originally Posted by Hellmark
There have been scientific studies that do show that devices with backlighting, or some other lighting system, do fatigue the eyes more, since you're more or less staring directly at a light. eInk does tend to be better since it uses ambient lighting, traditionally. However, any benefit you get from eInk goes out the window if you use the glow function of the Nook Glowlight, or similar readers, since once again you're staring directly at a light source.
Not quite. With a backlit screen, the light is being cast directly up into your eyes, so it's the angle of the light that fatigues some eyes more than the fact that there is light. With a frontlit screen, such as the Paperwhite that the OP is getting, you're looking at a light source still, but the angle of the light is entirely different - it shines away from your eyes. This provides a fundamental difference and vastly reduces eyestrain. It's really a remarkable technology.