Night Vision Potion causes night to appear day for the drinker, which makes seeing a lot easier. You can find these in a Potion Shop, or a Druid can make them. Since many prefer the day to the night, players often store Night Vision Potions in large quantities for future use. This potion normally lasts all night. However, logging off the Oberin game immediately cancels this potion, so if you log off and then return later that same night, it will appear as night again.