Stress

Stress is the short term effect of seeing Zombie nearby, hearing banging at your Door, hearing unsettling Noises, and generally anything which upsets the character (which will likely include annoying Survivor in the future). If nothing is bothering the character, his stress level begins to drop. However, while the character is stressed his Morale will decrease, which is a more long term effect and harder to change.

Stress can be lowered by killing Zombie (ultimately this would depend on the personality of the Player), sleeping, drinking Booze, taking Painkillers, or smoking Cigarettes.