Clay Routledge is a psychological scientist, and somewhat of an expert when it comes to what role nostalgia plays in giving us meaning in life. He kindly agreed to share some of what he's learned over the years. “The most interesting thing we have discovered is that nostalgia is actually better described as a future-oriented experience,” he told Bored Panda. "Yes, nostalgia involves looking to the past. But the reason people are nostalgic is because they need comfort, inspiration and guidance to move forward."

Routledge says nostalgia can be triggered by various external stimuli, like hearing an old song or running into an old friend, but we tend to become the most nostalgic when we are experiencing some kind of stressor and are in some way unsatisfied with our current situation. "Nostalgia increases optimism about the future, the motivation to pursue life goals, openness to new ideas and experiences, and creativity. In short, nostalgia energizes and inspires us," revealed the expert.

He further added that nostalgia doesn't just boost our wellbeing and motivation, it also helps us generate new ideas. "I've talked to artists, designers, filmmakers, entrepreneurs, and business leaders aspiring to create and innovate. All of them have nostalgic inspiration, meaningful memories that give them inspiration," revealed Routledge. "People who think nostalgia keeps us stuck in the past or serves as a barrier to new ideas don't understand that a healthy dose of nostalgia often plays a critical role in the creative process."

The Oxford English dictionary defines it as “a sentimental longing or wistful affection for a period in the past.” And it's generally seen as a positive emotion. But Routledge says it there are some cases where nostalgia can be negative.

"Nostalgia can be unhealthy if people become seduced by the idea that the past was better and it will never be that good again," he explained. "This kind of pessimistic nostalgia is a barrier to gaining the best benefits nostalgia offers as a guide toward self-improvement, innovation, and progress."

Thankfully, Routledge says most people experience nostalgia in a good way. "Typically, nostalgia is a response to, not a cause of, negative thoughts and feelings. And it helps people productively work through their worries by reminding them of what has made their lives meaningful and inspiring them to move forward with purpose," he told us.

"If people find nostalgia is making them feel more negative about the present and future, I would encourage them to rethink their relationship with nostalgia. It should be a source of good feelings and inspiration."

You might be surprised to know that nostalgia was once seen as a mental illness. "For centuries, nostalgia was thought to be synonymous with depression. During the Thirty Years War, several Spanish soldiers were discharged from the army with nostalgic symptoms," reads the Neuroscience Of site. "The term nostalgia - formed from the Greek 'nostos' (homecoming), and 'algos' (pain) - was coined by the 17th-century Swiss physician, Johannes Hofer, who considered it to be a mental disorder."

Interestingly, past research has found that people are more likely to feel nostalgic on cold days than on warm days. And that the fuzzy feeling we get with heart-warming memories can literally warm us up. "Our study has shown that nostalgia serves a homeostatic function, allowing the mental simulation of previously enjoyed states, including states of bodily comfort; in this case making us feel warmer or increasing our tolerance of cold," said co-author of the study, Dr Tim Wildschut.

According to another study, feeling nostalgic might even help relieve mild pain. Researchers from Beijing's Institute of Psychology of the Chinese Academy of Sciences gathered 34 adults and split them into two groups. One group was shown images that made them feel nostalgic. Think children's games or cartoon characters from the past. The second group looked at more modern images that didn’t evoke nostalgia.

After viewing each image, participants were exposed to a “heat-pain stimulation of varying intensity” on their right arm. And while this was happening, researchers were measuring their brain activity. The results showed that one group felt less pain than the other. And that “nostalgia triggers real effects in the brain by activating pain relief mechanisms, such as an analgesic effect.” Similar to taking paracetamol.

So, if your head hurts a little at the moment, there’s a chance you might feel better after looking at some of the images on this list of flashbacks.

Does the smell of cookies being baked remind you of your childhood? Or maybe a particular cologne or perfume brings back memories of your ex. There’s actually a science behind why certain scents stir up such strong reminders of past people, places or things.

As Inverse reported, "Smells from childhood are particularly powerful in this respect because very often our first exposure to scents is in childhood. Our brains form particularly strong connections during this process in case recollection of the smell is important for survival."

Routledge says that loneliness is a big nostalgia trigger. "Loneliness is tough because when people feel lonely they actually tend to withdraw from others to avoid further social pain, when they should be seeking out others as a way to not feel lonely anymore," he explained.

"Nostalgia helps. It reminds people of past social success, which reminds them that even though they are lonely in this moment, there is a way forward. If they have felt connected in the past, they can feel connected again."

Nostalgia breeds optimism and resiliency. And if there was one time we needed resilience, it was surely in the dreaded year of 2020. If you found yourself reminiscing more than usual during the Covid lockdown, you probably weren’t alone. Routledge says that nostalgia is a resource that people use to move forward. And boy did we want to move forward and fly into a future that didn’t involve Covid or lockdown.

Interestingly, nostalgia might have played a part in helping some of us get through those dark, lonely days. We daydreamed about the pre-pandemic times, when we could hang out freely with our friends and family, or just simply walk out our front doors.

“COVID lockdown was a time of health, social, and economic anxiety. Nostalgia not only provided psychological comfort by giving people a fun distraction. It gave them hope for the future by reminding them that life is bigger than one period of time,” said Routledge during our interview.

“They could use what was meaningful in the past to help them plan for the future. In fact, the pandemic inspired many people to really think about what is important in their lives, what the want to prioritize or not take for granted moving forward. Their nostalgic memories helped them plot that path.”

Ironically, a few years later, some people are now nostalgic for the days of face-masks, social distancing, and isolation.