The Benefits of Tree Hugging

My week started by wondering why I found a hike in the woods so calming, and ended with extensive research on olfactory systems.

It’s no secret that part of the reason I moved to British Columbia was for my health, and I’m not unique in that thinking. As an ex once said to me: “how can you be depressed when you look outside and see mountains?”

While that’s true, I’ve personally found that the biggest change in my health came from daily walks in the woods. Twenty minute hikes has significantly helped my ability to deal with stress and anxiety. Which got me thinking: why? What is it about the woods that I find so calming?

There are likely many answers, but one that I came across this week was my sense of smell. The first thing that I think of when I picture the woods is the smell of trees and dirt and wet moss.

With a little bit of research I discovered that olfactory systems are extensive and closely tied to cognitive, psychological, and physiological wellbeing, especially when it comes to the smell of trees.

So here’s what I learned this week:

Smell and Memory

Olfactory processes are unique, because they’re directly tied to the limbic system. The limbic system is the part of your brain that processes emotion, memory, and motivation. It includes the amygdala (emotion) and the hippocampus (memory), and when you get olfactory stimulation (i.e. when you smell things) the information is sent straight to the limbic system.

This is different from your other senses. Stimulation from vision, touch, or hearing is sent to the cerebral cortex, which the part of your brain that is all about reason, thinking, and problem solving.

This highway to your memory is part of the reason why smell has been closely tied to a sense of home, comfort, nostalgia, and relaxation. When tested, visual memory started to decline after four months while olfactory memory didn’t show signs of declining.

Anecdotally, this is likely why I smell fake strawberry and instantly remember a Strawberry Shortcake scented eraser from when I was six, but I can’t remember what color sticky notes are shoved in the back of my desk drawer.

Sense of smell and its connection to the limbic system can also participate in physical health, moods and stress management, and cognitive function, among other things. This is why a lack of smell (known scientifically as “anosmia”) impacts quality of life and wellbeing.

In other words, smells are essential to your wellbeing. And I found a couple of scientific studies that explain why.

Research

Of the three papers I read on this topic, two were experimental studies. One took a look at the physical and cognitive effects of isolated pine smells, and the other examined the reaction of participants to ecological stimuli in two woodland environments in Britain.

In the first paper, titled “An Experimental Study on Physiological and Psychological Effects of Pine Scent”, participants were exposed to pine scents in a secluded room with no other stimuli (in other words, they couldn’t see, they were just smelling pine needles).

Researchers were able to see that exposure to pine scents activated the frontal lobe, including the orbitofrontal cortex, which processes emotions, judgement, and perception. The participants needed about one minute of smelling pine for their brains to activate, and it was concluded that pine scent was promoting brain function.

While this study didn’t, other studies have shown that walking in a forest for 15 minutes lowered blood pressure, cited as lowered nervous system activity). What this likely means is that when there are additional sense stimulations instead of just smell (hearing, visuals, etc.) it results in whole body relaxation and improved function.

In the second study, “Nature, Smells, and Human Wellbeing”, participants walked around Sherwood Forest and Clumber Park in Britain for around half an hour, at which point they were asked to describe how they felt on their walk, without specifically prompting answers about smells, specific stimuli, etc.

The participants mentioned relief at getting away from overwhelming city smells and feeling refreshed and calm. Having a “clear mind” was also mentioned more than once. In summary, once their senses weren’t being overpowered, they had a mental reset and were able to relax, mentally and physically.

They also described an earthy smell that they connected with the roots of the trees, which gave them a feeling of connection with nature.

Most notably in this study, almost every person described the smells of their walk by relating it to a childhood memory. Even “bad” nature smells, like decomposition, were associated with positive memories.

“I got kind of a classic leaf mould smell. It was one of those smell-to-memory moments where, you know, I was suddenly back in the back garden with my Dad and I’m eight and he’s turning over the compost heap on an autumn morning on a Sunday. You know, I’m helping him out. So it was kind of quite an emotional moment, sort of getting that kind of connection.”

This takes us back to the last section, where we already know that smell is sent straight to the hippocampus to process, and that smell memory doesn’t show evidence of declining. Having such a personal connection with olfactory stimulus is also is also why studying smell is so difficult, because how a smell makes you feel is so personal to your own memories of that scent.

Overall, this second study found positive effects with physical health, relaxation, comfort, and rejuvenation.

Everything is Connected

We don’t experience the world through just one sense, and it’s difficult to study just one at a time. When you’re on a walk through the woods, you’re using all your senses to take in what’s around you.

Visuals of nature, sounds of the outdoors, and natural smells working together have been shown to be a powerful force of improvement for an individual’s cognitive and physical wellbeing, more so than just using one sense.

This is also important to remember when scrolling. I’m a photographer, I certainly love nature photos. And while some of them make me feel peaceful, it’s not doing nearly the same amount of good as putting my phone down and standing under a tree for a while.

The conclusion from both research studies was that while olfactory alone is very beneficial, using all of your senses during a minimum 15 minute walk through the woods will improve everything from cognitive wellbeing to emotional processing to stress reduction.

Conclusion: Leave the House

It really is as simple as that.

If a walk through your local woods or park isn’t helping, considering how closely smell and memory are related. Find which natural scents from your childhood bring back the strongest memories, and see how incorporating 15 minutes of that scent in your life improves your physical and mental health.