Will this “pine forest” diffuser placed on your teleworking desk really boost your productivity? Could a simple scent replace a walk in the woods and boost concentration? The idea appeals to essential oil brands and aromatherapy enthusiasts. There remains a very concrete question: breathing a smell of pine does it really make the brain more efficient? A German team has just tested the hypothesis in the laboratory, with a protocol rarely so solid for this subject.
How the Pine Smell Study Tested the Mental Boost
The study led by Djo Juliette Fischer of the Hamburg-Eppendorf University Clinic and Simone Kühn of the Max Planck Institute for Human Development disseminated essential oils of Douglas fir and Hinoki cypress to more than a hundred adults. Researchers from the University Clinic Hamburg-Eppendorf divided the 102 participants (average age 28.2 years, 53% women) into two parts. Everyone came to the laboratory twice, in a neutral room where a diffuser presented as a simple humidifier contained either water or an essential oil of Douglas fir or Hinoki cypress. The order of conditions was drawn at random for each person.
For approximately 75 minutes, each person completed seven standardized cognitive tasks measuring working memory, sustained attention, vigilance, mental flexibility and inhibitory control, then completed the mood and perceived stress questionnaires. An initial analysis suggested a slight improvement in vigilance with the Douglas fir, but this effect disappeared when the group increased to 68 people. The authors summarize: “Our results suggest that short-term exposure to these two essential tree oils does not produce immediate effects on the variables tested.“, explain Djo Juliette Fischer and Simone Kühn.
What science knows about pine smell and the brain
Numerous meta-analyses show that a real stay in the forest improves mood, reduces psychological stress and can support working memory or executive control. Biologists link part of these effects to terpenes emitted by trees, such as alpha-pinene and limonene, often mentioned in work on “forest bathing” Japanese. Old mini-studies on Hinoki cypress oil, with only 6 or 8 volunteers, sometimes even found more attention, sometimes the opposite.
The new work, much broader, points to a key element: the vast majority of participants simply do not recognize what they smell. In the second study on the Douglas fir, only 14.71% identified a forest or tree smell, while 73.53% spoke of a “citrus”, “flowery” or household product note. The authors write that “most participants could not reliably identify the odor, suggesting limited awareness and/or semantic associations“. In a very small subgroup of 14 people who correctly attributed the odor to a tree, we clearly see some signs of less fatigue and better inhibitory control, but these results remain exploratory.
Should you keep your pine scented diffuser?
In light of this data, a “pine forest” spray will not increase IQ or test scores in minutes. There is no robust evidence that the only smell of pine improves cognitive performance in the short term. On the other hand, this perfume can remain pleasant, relaxing, and serve as a personal ritual, especially if we consciously tell ourselves that it evokes a walk in the forest.
The authors suggest exploring mixtures of odors closer to real forest air, also measuring physiological stress parameters and, above all, making the “natural” origin of the odor explicit to activate the right mental associations. While waiting for this work, it is still real outings in green spaces, regular walking, sleep and stress management that constitute the best established allies for the brain.