A PC or NPC exposed to extreme mental exertion, soul-shivering horror, torture or bearing witness to unspeakable acts or sights can potentially suffer Stress. Some environmental effects can inflict Stress, such as surviving a particularly nasty battle, or spending several days without food. Stress can also be an effect of attacks from certain creatures. Checks to oppose gaining Stress are made against WIS.

A PC or NPC exposed to extreme physical exertion such as a lack of sleep, starvation, exposure to heat or cold, disease, or blood loss can suffer Exhaustion. Exhaustion can also be the effect of attacks by certain creatures. Checks to oppose gaining Exhaustion are made against CON.

As PCs and NPCs gain stress and exhaustion they weaken. They can choose to cure one level of exhaustion or one level of stress for each safe rest.

1. Disadvantage on any STR, DEX, or CON checks
2. Speed halved
3. Disadvantage on attack rolls and disadvantage on NPCs' morale
4. Hit point maximum halved
5. Speed reduced to 0
6. Death

1. Disadvantage on any INT, WIS, or CHA skill checks
2. Gain one of the following debuffs until stress is reduced to 0 (roll randomly):
   • Distracted - AC reduced by 2.
   • Dread - May take their Active action or Quick action each round, but not both.
   • Headaches - Proficiency bonus not added to checks.
   • Pessimism - Critical successes are treated as normal rolls.
3. Disadvantage on magic checks and attacks and disadvantage on NPCs' morale
4. Sleep does not heal exhaustion (nightmares)
5. Temporary insanity (The player experiences hallucinations, hears voices in their head, experience powerful urges to do things they normally wouldn't, and other mind-altering events.)
6. Permanent insanity and debilitation

I think stress and exhaustion make good bookends for the insanity system. It also gives bad guys yet another way to attack the party that isn't just hit points.