Psychological trauma, mental trauma or psychotrauma is an emotional response to a distressing event or series of events, such as accidents, rape, or natural disasters. Reactions such as psychological shock and psychological denial are typical. Longer-term reactions include unpredictable emotions, flashbacks, difficulties with interpersonal relationships and sometimes physical symptoms including headaches or nausea. Trauma is not the same as mental distress or suffering, both of which are universal human experiences. Given that subjective experiences differ between individuals, people will react to similar events differently. In other words, not all people who experience a potentially traumatic event will actually become psychologically traumatized. Some people will develop post-traumatic stress disorder after being exposed to a major traumatic event.