After a potentially traumatic event (PTE), many individuals experience either no distress or only transient distress, while others suffer considerable morbidity and may develop post-traumatic stress disorder (PTSD). Around one-third of people experiencing a PTE will develop PTSD, though this varies depending on the type of traumatic event and rates of PTSD are higher with type 2 trauma. Type 2 trauma involves repeated traumatic experiences over extended periods. Although PTSD symptoms can be present acutely, the diagnosis requires the persistence of symptoms for at least one month and the symptoms should cause functional impairment.