Nintendo has always recommended for you take a break from playing their consoles about every hour. Now with the 3DS, Nintendo states that different people have different reactions to 3D, so they recommend using the slider to adjust the 3D affect or stop playing games all together if you start feeling ill. Nintendo then takes it one stop further recommending that kids under 6 do not use any 3D device at all, stating that eyes of young children are still in a development age and long exposure to 3D can cause damage in the future.