BERLIN A growing body of research suggests that spending time outdoors, especially in forests, can improve mood, reduce stress, and sharpen mental performance. Yet as urbanization expands and green spaces shrink, scientists are increasingly exploring whether the specific elements of nature that drive these benefits can be recreated indoors.
A new study published in the Journal of Environmental Psychology suggests the answer may be more complicated than simply bottling the scent of trees.
The research pushes back against the increasingly commercialized idea that forest-inspired essential oils or “nature scents” can substitute for immersion in living ecosystems. While earlier studies on forest bathing (shinrin-yoku) have found measurable health benefits associated with spending time in forests, the new study found that isolated tree scents alone produced little measurable effect on mood, stress, or cognition.
Diana’s Woods in Nemi, Italy [MJTM
The findings add to growing evidence that the benefits associated with forests may arise from the full ecological encounter rather than from isolated natural products alone.
Indeed, as many Pagan paths and practitioners have long argued, healing emerges through relationship with living landscapes rather than through extraction alone.
The study focused on whether the scent of trees might explain some of the positive effects associated with forests. Forests contain airborne compounds released by trees, including terpenes and phytoncides, substances that earlier research has linked to stress reduction and immune benefits.
Researchers tested two tree essential oils: Douglas fir, a scent associated with Central European forests, and Hinoki cypress, a tree native to Japan and often associated with traditional Japanese forest bathing practices.
Participants completed a series of cognitive tests and psychological assessments in a laboratory setting while either the essential oil or plain water vapor diffused into the room. Because Douglas fir would likely be more familiar to German participants than Hinoki, researchers also explored whether familiarity with a forest scent mattered.
Initially, researchers observed a slight indication of improved vigilance among participants exposed to Douglas fir. However, after expanding the study with additional participants to strengthen the statistical analysis, the effect disappeared entirely.
A Norfolk Island Pine Tree in South Florida [MJTM
Across both studies, the researchers found no significant short-term effects on mood, psychological stress, working memory, attention, inhibition, vigilance, or executive functioning.
Importantly, the statistical analysis did not simply fail to find evidence of benefit. According to the researchers, the results found that no meaningful effect existed under the conditions tested.
One of the study’s most revealing findings involved scent recognition itself. Only about 15 percent of participants in the second Douglas fir trial correctly identified the odor as tree- or forest-related. Many participants described the scent instead as citrus-like, floral, or similar to cleaning products.
Among the small number of participants who did recognize the scent as forest-related, researchers observed tentative hints of reduced fatigue and improved inhibition performance. This suggests that psychological associations with forests — not merely exposure to airborne compounds, may play an important role in how humans respond to natural environments.
As the researchers noted, “most participants could not reliably identify the odour, suggesting limited conscious awareness and/or semantic associations.”
The researchers also acknowledged several limitations in the experiment. Participants were not explicitly told that scents were being tested, as the diffuser was presented simply as a humidifier. In addition, the 75-minute battery of cognitive tasks may itself have induced mental fatigue, potentially masking subtle effects.
Most significantly, the researchers noted that isolated essential oils cannot reproduce the full chemical and sensory complexity of an actual forest.
“A natural environment such as a forest comprises a variety of elements, including olfactory and visual elements,” the researchers wrote. “These odorants cannot fully reflect the complexity and diversity of actual forest air.”
That conclusion stands in contrast to a growing body of forest bathing research.
As previously reported by The Wild Hunt, a July 2025 study published in Frontiers in Forests and Global Change followed 36 healthy adults during a three-day forest bathing retreat in the evergreen forests of Tianjing Mountain in southern China.
Researchers tracked participants’ mood, sleep quality, immune function, and stress markers over the course of a month. Participants reported better sleep, improved mood, and reduced stress. The study also found increases in important immune cells, including T cells and B cells, along with higher levels of protective salivary compounds such as immunoglobulin A and lysozyme. Markers of inflammation and stress declined significantly during the retreat.
While that earlier study had limitations, including its relatively small sample size and focus on healthy young adults, researchers concluded that the findings provided “multifaceted evidence for the health-promoting effects of forest bathing.”
The new research on tree scents highlights the possibility that the restorative effects associated with forests emerge from a deeply multisensory experience, one involving sound, sight, movement, humidity, microbial exposure, ecological diversity, memory, symbolism, and psychological connection to place. As the researchers observed at the beginning of their article, “A deep inhale reveals the forest’s scent as the wind rustles the green leaves. Even though nature engages all our senses, this experience is slowly fading from daily life due to urbanisation.”
The new research suggests that forests may heal not because they can be bottled, but because they cannot.
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