How do I play this exactly? Sanity/Light and Darkness - please explain

[Zoridium JackL]

You might not like the answer, but: stay in the same place for a while. Find a candle or light one and huddle by it until your sanity restores. Or: like they said, pick up the pace and keep your oil well stocked by finding all the hidden stashes and keep your lantern itself lowish since the standing oil drums give you oil based on how much is in your lantern at the time.

it's acctually based on how much oil you have total, sooo, yeah, they can become pretty useless when you have a lot of oil, and if you play smart you will.