Modern cell phone AMOLED displays may be a poor choice for nighttime reading. They typically dim the screen brightness through the use of pulse width modulation (PWM) operating at the frequency of approximately 240 Hz. This is the same kind of low-frequency PWM found on early LED-backlit LCD displays that some users reported to cause them more eye strain than their previous CCFL-backlit monitors. I have not seen any medical study examining their complaints but companies like BenQ responded by publicly announcing "flicker-free" (i.e., PWM-free) monitors while others made the change quietly in their new product lines. We've seen PWM in LED backlights either phased out or configured to operate at higher frequencies (often >1000 Hz).
For an introduction to the whole PWM business, read http://www.tftcentral.co.uk/articles/pulse_width_modulation..... Personally, I do notice PWM flicker at 0% brightness on some screens (you at the very least see it as strobed residual images as you move your eyes across the screen). I am not sure if it has caused me any extra eye strain but I found it annoying enough to consciously go for PWM-free displays when purchasing kit. I wouldn't pick such a screen for nighttime reading specifically.
For an introduction to the whole PWM business, read http://www.tftcentral.co.uk/articles/pulse_width_modulation..... Personally, I do notice PWM flicker at 0% brightness on some screens (you at the very least see it as strobed residual images as you move your eyes across the screen). I am not sure if it has caused me any extra eye strain but I found it annoying enough to consciously go for PWM-free displays when purchasing kit. I wouldn't pick such a screen for nighttime reading specifically.