Fatigue: Burnout causes decreased sleep quality and quantity, leaving the person feeling fatigued throughout the day.
Carelessness: Burnout causes people to care less about things they once cared a lot about. It is like the mind does not want to deal with anything else.
Decreased Immune System: Stress causes a weakened immune system.
Irritability: Burnout can leave the sufferer on edge.
Moodiness: Lack of sleep and not dealing with burnout causes frustration.
Frustration: Feeling frustrated is common.
Depression: Depression can set it with burnout because, well, it is depressing.
Emotional Withdrawal: When someone experiences a burnout they will almost always withdraw from the outside world.
Health Problems: Burnout is caused by stress. Stress alone can reduce the effectiveness of the body's immune system. A person who is burned out will have a weakened immune system and when undealt with will most likely get sick.
Less Quality Work: When burnout strikes the ability to create the level of quality you did before seems to disappear.