(CNN)Having a hard day at work? Stressed out about deadlines or bosses or meetings? It may help to stare at a plant, according to researchers from Japan.
The researchers felt that a lot of employees underestimated the respite that plants offer from work-related stress, so they conducted an experiment on workers at an electric company in Japan and observed their changes in stress levels pre- and post-involvement with plants.
The findings, recently published in the HortTechnology journal, showed that the number of employees with high scores on an anxiety measurement test decreased their scores slightly. Another 27% of employees in the study showed a significant decrease in resting heart rate.
Many studies have been done on the health effects of indoor plants, but most of those were performed in either laboratories or quasi-office settings and only included passive interaction.
This study verified the stress-reducing effect of gazing intentionally at a plant for a few minutes and actively engaging in the care of it in a real office setting when an employee felt fatigued.
The results suggest that if employers provided active encouragement for workers to take three minute "nature breaks," the mental health of their employees would improve, said Dr. Masahiro Toyoda, lead author of the study and professor at the University of Hyogo, where he specializes in horticultural therapy.
The study is the "latest of those that continue to point out that plants are beneficial to humans," said Dr. Charles Hall, Ellison Chair of International Floriculture at Texas A&M University.
"It's something we inherently knew, but has suddenly been quantified. And so now, we're seeing the numbers behind the reasoning," he said.
Alleviating anxiety with plants
To gauge the employees' usual stress levels during days when they felt fatigued, the researchers used a measurement tool called the State-Trait Anxiety Inventory index (STAI) and recorded their pulse rates in the morning and night.
First, there was a week-long control period without plants during which the participants measured their pulse by hand when they felt fatigued, and then took a second reading after three minutes of gazing at their desktop.
The participants were then told how to water and care for the plants, and each chose one favorite plant.
During the remaining two weeks of the study, workers first measured their pulse under the same condition, but the second reading came after three minutes of gazing intentionally at the plant placed on their desk.
STAI scores decreased slightly after the intervention period, and the number of participants whose pulse rate lowered after a three minute rest also increased.
A decrease in pulse rate demonstrates sedation of your sympathetic nervous system, known as the body's fight-or-flight response.
Judging by positive feedback given by about half of the participants, the authors said affection for a plant of one's own may have played a role in reducing stress.
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.
Why a plant for stress reduction didn't work for everyone
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."