Flashbacks are not confined to
psychedelic states. Any highly
traumatic experiences may cause the subject to ocassionally experience a very vivid recollection of the moment, with
emotions and
sensory memories so vivid that it feels like they're back in it. Flashbacks are a primary symptom of
PTSD (post-traumatic stress disorder), a common affliction among rape victims, disaster survivors, and battlefield veterans.
It seems likely that flashbacks can also occur to states of
ecstasy and
enlightenment, although psychology has long shown a bias towards
pathology, meaning that these have been less-studied.