Kathy Willis is a professor of biodiversity at the University of Oxford. She has presented on several BBC television and radio programs. Her previous book, Botanicum, was awarded the Michael Faraday Medal for Public Communication of Science from the Royal Society in 2015.
What’s the big idea?
Scientific evidence continues to prove increasingly detailed ways in which nature boosts psychological and physical health. From lowering stress using botanical visuals and the pain-relief of natural sounds to feeling sustained joy and vigor after going outside, our scientific understanding of why nature benefits us is only growing.
Below, Kathy shares five key insights from her new book, Good Nature: Why Seeing, Smelling, Hearing, and Touching Plants is Good for Our Health. Listen to the audio version—read by Kathy herself—in the Next Big Idea App.
1. Plants reduce stress.
Looking at green plants on your desk, a computer screensaver, or outside your window for as little as a minute automatically triggers changes in the body which alleviate physiological and psychological stress. These automatic changes include lowering the heartbeat, increased activity to areas in the brain associated with calming, and psychological measures indicating a reduction in anxiety.
Several clinical studies show this, but one of my favorites is one where participants were made to sit at a desk with a computer screensaver of either a forest view or an urban scene. Whilst sitting at their desks, various clinical measures were taken to assess the participants’ physical and mental state. Within 90 seconds, significant differences emerged, showing that people looking at green nature were much calmer (physically and mentally) than those looking at urban images.
This doesn’t just happen when you are already feeling calm in the first place. Other studies show that if you have a stressful incident, stress levels reduce quicker when looking at green plants or a green horizon. The next time you feel stressed, look at some plants or a natural landscape. It will cause you to become physically and mentally calmer.
2. Certain nature sounds provide pain relief.
When entering hotel lobbies or health spas, it is common to hear sounds of nature played over the speakers. I was curious about what impact nature sounds have on our bodies, and what I found should make all of us remove our headphones when walking through a park.
When we hear the songs of bird species such as robins, warblers, and thrushes, or the rustling of wind through leaves, or the gentle trickling of streams, the same sorts of reactions are triggered in our bodies as when seeing green vegetation. That is, automatic changes occur in our nervous system such that we become less physically and mentally stressed.
“Patients hearing nature sounds had significantly lower salivary amylase levels and reported lower pain scores.”
However, not all sounds of nature are calming. Understandably, the growl of a lion would not make anyone calm. The loud screeching of crows and other large birds—where their sound is a short, punctuated, loud noise rather than a tuneful, melodic song—can increase stress. These findings track around the world, with studies done in the U.S., Europe, and Japan all supporting the idea that nobody finds the sound of screeching birds calming.
Remarkably, hearing certain sounds can reduce pain levels. In one experiment, researchers studied participants in a hospital who were having surgery whilst still awake. They compared three groups: the first wore noise-canceling headphones, the second listened to recordings of nature sounds, and the third group heard the background noises in the hospital. During and after the operation, patient pain was measured using a well-known pain score index and stress was measured by testing levels of the enzyme amylase in their salvia. Amylase is known to be released in greater quantities when we are stressed. They found that patients hearing nature sounds had significantly lower salivary amylase levels and reported lower pain scores. Hearing nature reduced stress and pain.
3. Smelling plants brings them into our bodies.
When you smell plant scents, you don’t just breathe them in and out. Instead, some scent-creating molecules pass across the lung membrane into our blood. In effect, part of nature becomes incorporated into our bodies.
For instance, an experiment was conducted on people walking through a pine forest. Pine forests have a distinctive, piney smell due to the scent molecule pine trees release called pinene. Researchers measured how much pinene was in participants’ blood before and after walking in the forest for two hours. They found that before walking in the forest, there was barely any pinene in the blood, while afterward, there were significant amounts.
Many plant scents have been shown to have positive and important impacts on our health once they are incorporated into our bodies. Smelling lavender makes a person less anxious and sleep better—it is not just an old wives’ tale. Lavender has compounds that affect the same biochemical pathways as anxiety-reducing drugs. When researchers studied the effects of lavender on sleep quality, they found that participants exposed to it during sleep had longer intervals and deeper sleep patterns—both known to be extremely important for health.
“Smelling lavender makes a person less anxious and sleep better—it is not just an old wives’ tale.”
Additionally, inhaling the woody-peppery scent emitted by trees such as cedar and Japanese cypress appears to offer another key health benefit. Numerous experiments, conducted with participants both in clinical settings and while walking through forests, have demonstrated that after inhaling these compounds, participants showed significantly elevated levels of natural killer cells in their blood. These levels remained elevated for several days following exposure. Natural killer cells attack cancer and virus cells. Therefore, we should all seek these elevated levels, as they provide an essential defense mechanism against serious diseases.
4. Touching wood or plant leaves can reduce blood pressure.
Several studies have compared individuals’ heart rate and other stress indicators when stroking a wood surface, aluminum, or glass. Results concluded that touching wood seems to make us calmer—perhaps like stroking an animal. Now that you know this, watch how many people stroke a wooden surface when they enter a room or touch a plant leaf as they walk by it. This is very common and something that we seem to do subconsciously. Now we know it has a health benefit and triggers calming.
5. Walk or run in a park instead of on a sidewalk.
Many studies indicate that you receive greater health benefits from walking or running in a park or among trees than on an urban sidewalk. In one study, male participants walked for 15 minutes at the same pace, in similar weather, without consuming coffee or alcohol in the past 24 hours, but in different locations. Those who walked in the park exhibited much calmer demeanor, lower blood pressure, and greater happiness.
There seems to be a critical length of time for walking in green spaces to gain these health benefits. Another study had participants, consisting of faculty and staff at the University of Michigan, undertake a nature experience (sitting, walking, or a mixture of both) in a park three times a week over an eight-week period. They found that the greatest reduction in stress levels occurred after 20 minutes. There was no significant additional benefit from spending more time, but less than 20 minutes resulted in minimal benefits. The maximum benefit appeared to be gained by those who both sat down and walked.
You only need to spend around 20 minutes in nature a few times a week to gain many significant physical and mental health benefits. Also, many of nature’s benefits can be gained indoors with house plants, flowers, and smells. Don’t wait to be prescribed nature. Start immersing your senses in nature daily for your health and well-being.
To listen to the audio version read by author Kathy Willis, download the Next Big Idea App today:
