A flashback is a suddenly coming up involuntary (reverberation) memories that can occur briefly and then disappear again. They are triggered by a so-called trigger (key stimulus), which ensures that the memories are relived. Flashbacks are often triggered by key stimuli from childhood, such as sounds, smells, places, or images. However, flashbacks can also occur in the context of mental illness or substance abuse. As a rule, the memories last a few seconds to minutes and can be accompanied by a wide variety of feelings, such as sadness, fear, disgust, anger, but also joy. Physiological accompanying symptoms that may occur include trembling, sweating, rapid heartbeat, dry mouth, or freezing. In hypnosis, sudden memories can arise arbitrarily and be processed by the hypnotherapist in a guided manner. In the hypnotic trance, the client gains access to his subconscious, in which there are also those memories that are not accessible to the conscious mind. So it may be that repressed memories show up in hypnosis - even unconscious potentials. It can be healing to work through and re-evaluate stressful memories and events.