Minecraft wiki entry for Tips_and_tricks, associated text: Trying to see ores in dark places is very hard for the eyes, and you might encounter vision problems. To avoid that, change the brightness by going into Settings > Video Settings then look for the slider named "Brightness". By default, the game has a "Moody" brightness setting. Set it up to a higher level ("Bright" is recommended). This will save the player's vision because you don't have to squint too much to see things. However, it won't let you see much in real darkness, and it won't affect monster spawning. This trick is especially useful in the Nether, where everything is somewhat lit without torches on a "bright" setting, and some mobs spawn at any light level.