PTSD symptoms can appear within one month or years after a traumatic event, impairing work, relationships, and daily functioning through four main categories: re-living the trauma (flashbacks, nightmares, intense reactions to reminders), avoidance (isolating from triggering people, places, or activities), negative mood and thinking (hopelessness, memory problems, emotional numbness, blame), and increased arousal (irritability, being easily startled, sleep and concentration difficulties, self-destructive behaviors). Children may additionally show delayed development, re-enact events, and experience sleep disturbances.