Sanity

Sanity is a stat in The Forest that was added in update v0.29. Having sanity under 90% is required to be able to build effigies.

Gameplay
Sanity can be viewed by accessing the stats page of the Survival Guide.

Sanity works as a formula. You start with 100% which is the max value, and 0% being the lowest value. Certain actions will raise or lower it.

There is only one patch note that mentions sanity. It was from its release and its information is quite limited:
 * New “Sanity” system. Sanity goes down when killing an enemy, chopping limbs, a lot when eating an enemy and slowly while in caves. Sanity goes up when sleeping, listening to music, eating fresh non limb meat and slowly while restoring energy on bench. Viewable in stats page of book.

What lowers sanity

 * Killing enemies, including cannibals and mutants
 * Cutting off cannibal arms, legs and heads
 * Eating arms, legs and heads
 * Spending time in caves

What increases sanity

 * Listening to music through the cassette player
 * Sitting down on benches, chairs, bone chairs and couches
 * Sleeping
 * Eating fresh meats which include lizard meat, rabbit meat, meat, small meat, and fish

Mechanics
The following table outlines what has positive or negative effects of sanity:

What does sanity do?
It has been confirmed that Sanity has no effect on the player whatsoever. The developers had plans to incorporate effects, however at this stage it has no effect. The only thing it does is allow the player to build effigies.
 * There is a theory that sanity causes auditory hallucinations, though this has never been confirmed. In the game files, there isn't anything linked to sanity as an effect, only what raises and lowers it.
 * I played with 0 sanity for over an hour whilst recording. I removed the background noise from the footage and attempted to analyse the sound for differences. There were no differences in audio to indicate that auditory hallucinations are an effect of low sanity --Farket8238 (talk) 05:43, 1 January 2018 (UTC))