The contrast of just your screen and focusing in the dark is likely damaging on its own; but you can add the red filter, and, if using kindle app, make the font white on black background.
But yes, as Kindles imply, reading text printed without a backlight is preferable to backlit text, so prefer lights over the backlight.
But yes, as Kindles imply, reading text printed without a backlight is preferable to backlit text, so prefer lights over the backlight.