This might explain why houseplants are so popular again.
It’s often been suggested that talking to one’s plants is good for the plants. But what if we have it all backwards; what if it is the humans who benefit from these little chit-chats? If you think about it, that the sound of our voice may help plants is pretty anthropocentric. They’ve been thriving forever without us, but we could not exist without them.
We rely on plants for their gifts of oxygen and food, for starters. But exposure to them – from spending time in nature to having a few houseplants – also does incredible things for our health and well-being. This is especially well illustrated by a study that was published a few years ago in the Journal of Physiological Anthropology.
The researchers set the stage for the paper by introducing this simple but profound truth:
"The living space of modern people has moved from outdoors to indoors – more than 85% of a person’s daily life is spent indoors."
They explain that a life indoors is made increasingly possible thanks to advances in information technology, which allows us to “connect and remain connected to the computer environment,” as they put it. Or, as I put it, which allows us to work, socialize, learn, shop, and entertain ourselves ... without ever having to step foot outside.
“However, this diffusion of information technology causes a great deal of stress, such as technostress,” the authors explain, “which is a modern disease of adaptation caused by an inability to cope with the new computer technologies in a healthy manner.”
Uhm, does that ring a bell for anyone?
So, enter the plants. There has been plenty of research looking at the health benefits of nature and houseplants as well. Indoor plants have been a popular topic of study and have been found to enhance job satisfaction in the office, reduce psychological stress, improve moods, and enhance cognitive health. These effects can positively affect resistance to diseases and chronic stress, explain the authors, but few studies have examined the actual physiological mechanisms that are at play.
Thus, the research team decided to look at the physiological benefits of indoor plants in modern people, focusing on the cardiovascular changes that happen when a person interacts with a plant. They measured autonomic nerve system activity, as well as quantifying the psychological changes during the contact with plants.
Granted, the study was pretty small – and limited in demographics: 24 men all around the age of 25 years. But the results resonate nonetheless. You can read about the methods in the study itself, but the condensed version goes something like this: Half the men repotted a plant while the other half were assigned computer tasks; the next day, each group did the other activity. Data for heart rate variability, blood pressure, and pulse rate were collected before, during, and after.
With the heart rate variability (HRV) they could measure activity of the parasympathetic nervous system (which increases in a relaxed state) as well as the activity of the sympathetic nervous system (which increases in a stressed state).
The participants also filled out self-rating assessments about their feelings before, during and after the tasks.
It may come as little surprise that the men felt “comfortable, soothed, and natural” after transplanting a plant; and they felt “uncomfortable, awakened, and artificial” after the computer task. And in fact, there were significant differences between the two after the tasks, despite the absence of significant differences in these feelings before the tasks, when they mostly felt neutral.
The physical changes were also significant, with the authors concluding:
“The results of HRV analysis indicate that indoor plants have positive physiological effects on the autonomic nervous system by suppressing sympathetic activity, which often increases when a subject is exposed to a stressor.”
In contrast, the computer task increased sympathetic nervous system activity and increased diastolic blood pressure as well.
In the end, the researchers say that active interaction with indoor plants can have positive effects on our stress response vis-a-vis cardiovascular activities. And that the physiological benefits may result from a number natural stimuli acting on the senses of vision, hearing, touch, and smell.
“Our results suggest that active interaction with indoor plants can reduce physiological and psychological stress compared with mental work.” they conclude. “This is accomplished through suppression of sympathetic nervous system activity and diastolic blood pressure and promotion of comfortable, soothed, and natural feelings.”
Given that we have mostly moved indoors, away from the nature that we have evolved with – and now remain inside and so closely connected to this relatively new concept of computer technology, is it any wonder that we are wired to respond to the living, green things around us?
And on that note, I’m going to go pet my plants ...