I read a lot, especially at night, on my Nexus 7 tablet, so eye strain and fatigue is always a concern for me. I’ve found ways around this to a large extent by enabling sepia tone mode in Google Play Books but it only goes so far. Google seems to agree and with the latest update to the eBook reader app, they have created a Night Light mode. Using information based on the amount of sunlight available, the app will gradually change the temperature and brightness based on that information.
When turned on, Night Light gradually filters blue light from your screen, replacing it with a warm, amber light as the sun sets. Night Light automatically adapts to the amount of natural sunlight outside based on the time of day, giving you just the right temperature and brightness. The color adjustment is more comfortable on your eyes and greatly improves low-light night reading.
Essentially, if you have been using the Sepia mode like I have in Google Play Books, this is an automatic version of making this change plus it adjusts the brightness. It is a bit genius.