Yearning for the past was considered a mental disorder in the 17th century when Swiss physician Johannes Hofer was attempting to diagnose the need soldiers felt to return home. He coined this yearning “nostalgia” and considered it to be a cerebral disease, according to Scientific America. Now, we see this yearning as a comfort, a socially acceptable way to sigh and dream for those Christmas mornings, Disney movies and ice cream drippings in the stressful and tense moments of life. The childhood comforts we took for granted for so long come back to warm us in the turbulent and developmental years of becoming an adult.

Nostalgia is not an emotional state, but rather “a longing for a sanitized impression of the past,” according to Alan R. Hirsh in “Nostalgia: a Neuropsychiatric Understanding.” Rather than seeing the past for what it truly was, we recall it as a conglomeration of various memories, filtering negative ones out to integrate the positive ones which creates nostalgia.

Professor David Gerber of the University at Buffalo has studied the ways in which nostalgia has changed over time, and has noted that only recently has society recognized nostalgia as a beneficial force.

“[There are] positive uses to which memory, even painful memory, may be put in the effort to confront the challenges to personal identities of such massive changes in the lives of an individual,” Gerber said.

This may be why nostalgia is most dominant among young adults, according to Erica Hepper, a psychologist at the University of Surrey. As life becomes more settled, people become less nostalgic. These memories help when shaping our identity to times of great change, such as leaving home and going to college. Nostalgia is actually a useful technique to help stave off any negative feelings due to the turbulence of becoming independent. Recollecting these positive emotions of a time we consider to be more simple and positive can help counteract emotions of anxiety, loneliness and depression. Recalling a love for the past helps promote hope for the future, and reassures us that life is meaningful.

Recalling a love for the past helps promote hope for the future, and reassures us that life is meaningful.

There are also key differences between nostalgia, homesickness and recollection that should be noted. According to Gerber, recollection is “a conscious and intentional effort” when trying to remember past memories. This is different than nostalgia, which is usually prompted by the senses, and is often a sudden experience. Nostalgia is ambiguous and is often a “flood of feeling[s] that diverts us temporarily from the present and immerses us in the past.” While nostalgia is usually positive, homesickness can be painful. Nostalgia passes while homesickness lasts and can be an almost obsessive desire for a certain place, which can lead to depression. Nostalgia helps people to cope with negativity; when in a lonely or poor state of mind, special moments are recalled to help deal with current problems. People who experience more anxiety tend to become nostalgic in order to help soothe their inner worries, according to Science Friday.

Nostalgia is ambiguous and is often a “flood of feeling[s] that diverts us temporarily from the present and immerses us in the past.”

Nostalgic Triggers

Smells and music in particular can be conducive to nostalgic feelings. Freud realized in 1908 that there was a strong link between odor and emotions. This is because the nose is connected directly to the limbic system of the brain, where emotions are housed. The average person can detect about 10,000 different odors, and each one will cause people to react differently, as they associate these smells with different experiences, according to Elite Daily.

“Olfactory has a strong input into the amygdala, which process emotions. The kind of memories that it evokes are good and they are more powerful,” said Howard Eichenbaum, director of the Laboratory of Cognitive Neurobiology at Boston University, to NBC. This helps to explain why nostalgia often results in positive emotions. The amygdala is the portion of the limbic system that causes intense emotions and motivation. When odors are being directed directly into this portion of the brain, one is more likely to be overcome with intense feelings. The limbic system is also home to the hippocampus, whose main functions include both memory and emotion. Since the nose is connected to two portions of the brain that are so important to memories and feelings, there is a very strong chance that nostalgia will be induced by odors.

The smell of baked goods were found to be the greatest olfactory stimuli of nostalgia. Other scents related to cooking (such as pasta, bacon and meatballs) came in second to the olfactory causes of nostalgia, according to a BBC report.

Other senses can play into nostalgia as well. Playing a song from a generation's youth can get a crowd of people excited. For example, an otherwise forgettable Avril Lavigne song that was popular in 2007 can transport you back in time because "Girlfriend" can remind you of being 12 years old. It has been found that songs that were on the radio during one’s childhood will make a person feel more attached to them. They will be more recognized and help trigger memories of that time.

These musical preferences were found to be inherited. In 2012, Cornell University and UC Santa Cruz discovered that college-aged students that were around 20 years old felt nostalgia for not only music played during their own childhood, but also for songs from the 1960s and 1980s, which were popular before their birth. Music that was popular long before they were born created just as much nostalgia as songs that were constantly on the radio as a youth. They theorized that parents passed down their musical tastes to their kids by playing the tunes frequently in developmental years, and passed down musical preferences inherited from their own parents played during their own youth, according to Priceonomics.

Nostalgia clearly has many benefits; however, it may be wise to avoid playing too much Justin Bieber around your kids if you don’t want them to be getting touchy feelings when “Baby” comes on the radio in 20 years.