The authors point to theories and perspectives emphasized in previous studies as a basis for why their experiment worked.
From the perspective of attention restoration theory -- which asserts that people can concentrate better after spending time in, or looking at, nature -- previous research found what it called "soft fascination" is important to recovery from stress. A desk plant in the current study "provided the opportunity for soft fascination in the office environment," the authors said.
Taking care of a plant didn't ease the stress of all the employees in the study. Some workers saw their pulse rate or anxiety levels increase, and some saw no significant change.
To avoid participants feeling anxious when their plants withered or died, the authors kept more plants at the ready for a swap. But according to Hall, this may not have mattered for people who experience anxiety on a regular basis.
"I think the anxiety among those in the study where their anxiety increased, it was because of that particular phenomenon that all of a sudden they're responsible for taking care of a plant and then all of a sudden the plant's not doing well and they have some anxieties from that," he said.
Some people could have gotten used to the plants and were no longer affected.
"There have been some pieces of evidence related to human stress reduction by nature with plants or by plants," Toyoda said. "However, when we get accustomed and/or bored to the same scene, the stress recovery effect will not continue so long."
The study was performed with 63 employees between the ages of 24 and 60, who worked on desktop monitors for traditional 40-hour work weeks.
Improve Your Well-Being with Nature
The researchers cited a distressing rate of stress and mental health disorders suffered by workers in Japan as motivation for conducting their study.
"The adoption of greenery into the office environment is becoming widespread as the need for improving mental health becomes greater," they said.
If you can't keep a plant on your desk, there are other things you can do to reduce stress during those long days at work.
Hall suggests that gazing out of a window could have similar effects, or taking a short walk outside of your building.
Regularly spending time in nature is always a good idea -- according to a 2019 study, just two hours per week is enough to improve your health and well-being.
"To get good effects of stress reduction brought by a small plant, let's enjoy the time of 3-minute gazing at the plant without thinking or words," Toyoda said. "This state is similar to that of mindfulness, which pays attention to the present moment."