Combat stress reaction, in the past commonly known as shell shock or battle fatigue, is a military term use to categorize a range of behaviours resulting from the stress of battle which decrease the combatant's fighting efficiency. The most common symptoms are fatigue, slower reaction times, indecision, disconnection from one's surroundings, and inability to prioritize. Combat stress reaction is generally short-term and should not be confused with acute stress disorder, post-traumatic stress disorder, or other long-term disorders attributable to combat stress although any of these may commence as a combat stress reaction.