When a character gains a level of fatigue, they acquire the Fatigued condition. If they gain additional levels of fatigue, the effects worsen. Fatigue is most typically gained when a character falls below 0 SP or spends/loses SP when they are at 0.

LevelsEffects
Fatigued (1)-10 penalty to all tests
Exhausted (2)-20 penalty to all tests
Drained (3)-30 penalty to all tests
Unconscious (4)Character falls Unconscious
5+Character dies