People who have experienced a traumatic event, e.g. a situation that poses an existential threat to themselves or others, such as an accident, the death of a loved one, war or violence, often have gaps in their memory of the traumatic event. The cause is an overstraining of the psychological defence mechanisms, as those affected find themselves unprepared in an extreme situation with intense feelings such as extreme fear, panic, loss of control, being at the mercy of others, helplessness, loss of security, despair and powerlessness. On the one hand, this can lead to memory loss because the brain is unable to process the incoming information and is overwhelmed by the flood of stress hormones and emotional influences; on the other hand, forgetting is also a protective mechanism to deal with the experience. This can lead to complete memory loss (amnesia), but even if only parts of the experience appear to have been erased from memory, the brain is highly sensitised and can react with severe stress in situations that remind us of the event. This can be triggered by certain odours, sounds, voices and other stimuli, although the connection to the trauma is usually not consciously established.