If a character has less than 10 Sanity and takes Sanity damage, He must test to resist Temporary Insanity, in addition to any effects from Sanity Shock. The character tests Will + Nerve. The difficulty is equal to the amount of points under 10 that the character's Sanity is at. If the character fails this test, he is Broken until he restores two or more Sanity points. In addition, the character suffers from a temporary mental health effect until his Sanity is restored to its maximum. This effect will often impose a penalty on rolls which might increase in certain situations. as determined by the GM.
If a character botches a roll to resist Temporary Insanity, he loses the rest of his Sanity and undergoes the Derangement process.