Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer).
Post-traumatic stress disorder (PTSD) can be an acute, chronic or delayed reaction to a traumatic event. Symptoms can include intrusive, disturbing flashbacks or nightmares of the event, accompanied with anxiety and disturbed sleep.