written by the home doctor cairns team

Have you ever smelt something which instantly took you back in time? Maybe to a country you’ve travelled through or moments in your childhood. Well, you’re not the only one.

According to Doctor Amanda White, a research technologist at Penn State College of Medicine, smells have the power to prompt flashbacks to previous life events.

It’s known as “odour-evoked autobiographical memory” and the reason it happens is likely due to brain anatomy. She says the part of our brain that processes smells is next to sections that deal with memory and emotions.

“Incoming smells are first processed by the olfactory bulb, which starts inside the nose and runs along the bottom of the brain,” Dr White wrote in Psychology Today.

“The olfactory bulb has direct connections to two brain areas that are strongly implicated in emotion and memory: the amygdala and hippocampus.”

The close relationship between these parts of the brain is one of the reason odours can spark nostalgia. A video by the SciShow team explains the technical stuff in more detail.

Scents can trigger PTSD: study

“Unfortunately, smells can also be potent triggers of negative emotions, particularly in individuals with posttraumatic stress disorder (PTSD),” Dr White said.

Research published in the The Journal of Clinical Psychiatry examined case studies of individuals with PTSD who experienced this “phenomenon”.

“One patient frequently experienced disturbing memories, feelings of guilt, and nausea when smelling diesel,” she said.

“On one occasion, the smell of diesel from a fire … conjured the memory of an accident in Vietnam.

“In his mind he could vividly see the burning vehicle, doors ajar, and billows of fire and smoke.

“He couldn’t save his fellow soldiers that day … it caused him to re-experience the overwhelming feelings of guilt and helplessness that he initially experienced more than 30 years ago.”

Sniffing out forgotten memories


According to psychologist Tom Stafford smell is “unique” among the senses.

“If we look at the major pathways travelled by the other senses, such as hearing and vision, they start at the sense organs – that is, the eyes or the ears – and move to a relay station … before passing on to the rest of the brain,”

“Smell information travels directly to the major site of processing … with nothing in between.”

Dr Stafford says because of this and the fact smells bring up emotions they can trigger deeply hidden memories.

“When we come up with a story about our memories, we start remembering the story as much as the raw experience,” he said.

“The smell is not only enough to relive that experience but it is also enough to pull out the rest of the memories along with it.”