How Sanity Works in Call of Cthulhu
Complete guide to the Sanity system in Call of Cthulhu 7th Edition. Learn about Sanity checks, temporary and indefinite insanity, and how to protect your investigator's mind.
Overview
Sanity is the mental health currency of Call of Cthulhu. As investigators confront the unknowable horrors of the Mythos, their minds strain and eventually break. Managing Sanity is as important as managing hit points.
Starting Sanity
Your starting Sanity equals your POW characteristic. Maximum Sanity is 99 minus your Cthulhu Mythos skill (the more you know, the less sane you can be). This creates a tragic irony: learning about the Mythos helps you fight it but permanently damages your capacity for sanity.
Sanity Checks
When encountering something horrifying, roll 1d100 against your current Sanity. Success means you lose the minimum Sanity listed; failure means you lose the maximum. For example, "0/1d6" means 0 on success, 1d6 on failure. Some horrors (like seeing a Great Old One) have no success option.
Temporary Insanity
Losing 5+ Sanity points in a single encounter triggers a temporary insanity check. Roll INT × 5 - if you succeed, the horror sinks in and you suffer a bout of temporary insanity. This lasts 1d10 hours and manifests as phobias, amnesia, violence, or other symptoms. The Keeper determines the exact effect.
Indefinite Insanity
Losing 20% of your current Sanity over the course of a single game session triggers indefinite insanity. This is more severe and lasts until treated. Your investigator gains a permanent phobia, mania, or disorder that affects roleplay. Treatment requires 1d6 months of therapy.
Recovering Sanity
Sanity can be recovered through: completing investigations successfully (Keeper awards 1d6+), therapy during downtime, improving skills (1d2 per skill improved), or defeating Mythos creatures. However, your maximum Sanity is permanently capped by your Cthulhu Mythos skill.
Quick Tips
- Keep track of Sanity losses within each game session to monitor insanity thresholds
- Invest in Psychology skill - it helps with therapy and resisting mental effects
- Build Sanity recovery into downtime between investigations
- Accept that some Sanity loss is inevitable - it's part of the horror experience