When a scent brings relief, it may ease a burden on the mind or evoke a place remembered fondly. What different experiences are contained in the single word relaxation?
A study published by Hosokawa and colleagues in 2025 aimed to measure subjective relaxation while smelling a scent using a short questionnaire. Japanese adults tried four scents, and patterns in their responses were used to develop a 12-item scale called the RSFF. A notable finding was that personal nostalgia emerged as one dimension alongside feelings of mental and physical release and negative emotions.
Developing a short questionnaire suited to the experience of scent
Relaxation can be investigated through physical measurements such as heart rate or by asking people how they feel. General mood questionnaires, however, may not fully capture experiences specific to scent. The researchers sought a tool that would describe the immediate state of someone smelling a scent in concrete terms with only a few questions.
They began with 5,084 consumer responses describing changes experienced when a scent did or did not make them feel relaxed, together with items proposed by fragrance specialists and researchers. After removing duplication and making other adjustments, they reduced these to 68 items. A pilot survey of 17 people then led to 38 items for the main survey.
The main survey recruited 110 healthy Japanese-speaking adults, and the first analysis included 101 after excluding responses that did not follow instructions. Participants were aged 18–69. While smelling four scents delivered to their homes, lemon-lime, strawberry, coffee, and vanilla, they rated how well each item described their experience.
Testing took place over two days, each beginning with an odorless sample followed by evaluations of two scents. Scent order was balanced across participants. The same people were surveyed again seven weeks later. The second analysis included 89 people, and 82 had usable data from both surveys for the test–retest analysis.
Responses grouped into three dimensions
The researchers used factor analysis to group responses that varied in similar ways. For example, if people who felt mentally lighter also tended to report feeling physically lighter, this would suggest a shared dimension. Here, factors organize relationships among responses; they do not mean that three devices were found inside the brain.
The final 12 items formed three dimensions. The first was release, including freedom from stress and a sense of mental and physical lightness. The second was nostalgia, linked to one’s personal past, such as childhood or hometown. The third was negative emotions, including anxiety, tension, tiredness, and boredom.
The items generally showed good coherence in both the first and second surveys. Data from the second survey also supported the three-dimensional structure. However, different methods for deciding the number of factors suggested different possibilities, so choosing three also involved the researchers’ judgment about interpretability and other considerations.
Scores measured seven weeks apart had a correlation of 0.65. This indicates some consistency when people were asked again using the same procedure. It does not mean that the effect of the scent smelled initially lasted for seven weeks.
Nostalgia is more than simply feeling good
In the second survey, the researchers also compared the RSFF with POMS, a widely used mood questionnaire. The RSFF total score and release dimension were positively associated with scores related to vigor. Nostalgia, however, showed no significant association with any of the POMS subscales examined.
The authors suggest that nostalgia may combine warmth with feelings such as wistfulness, making it difficult to capture solely in terms of pleasant or unpleasant mood. Participants had not been placed under intense stress, and their negative-mood POMS scores tended toward the low end. This condition is also important when considering comparisons between scales.
Given that scents can bring back past scenes and emotions, an important implication is that including nostalgia may make measurement better suited to scent experiences. The authors also suggest that familiar scents might be associated with a sense of reassurance. However, they did not directly test that mechanism, nor did the study demonstrate the safety of nostalgic scents.
Memories differ from person to person. Even for the same scent, the past it evokes may contribute to individual differences in relaxation. A distinctive feature of this scale is that it includes nostalgia in measurement rather than dismissing it as an incidental emotion.
Investigating experiences rather than ranking scents
An additional analysis found higher RSFF scores for the lemon-lime sample than for the other three scents. A method in which participants indicated their degree of relaxation on a single line produced similar results, with a correlation of 0.73 between the two measures. This supports an association between the scale and participants’ own sense of relaxation.
However, the study’s main purpose was scale development. Its principal analyses used responses given while smelling scents rather than changes from the odorless condition. Comparing these four samples does not establish that any fragrance works best for everyone or can treat anxiety or depression.
Furthermore, the 404 observations from 101 people evaluating four scents do not represent 404 separate people. Future analytical models need to address repeated responses from the same individuals more explicitly. Participants were limited to Japanese speakers living in Japan, and further validation is needed to establish whether the scale works across different home environments, scent types, cultures, and life experiences.
The research was funded by Takasago International Corporation. Three authors were employees of the company, and the fourth was a technical adviser paid by it. The study did not yet examine how the scale corresponds to physical responses such as heart rate or brain waves.
Summary
Relaxation while smelling a scent may involve more than reduced tension: it may also encompass a sense of mental and physical release and personal nostalgia. This study provided a foundation for examining that experience through 12 items.
The authors’ next aim is to combine the short questionnaire with heart-rate and brain-wave measurements to investigate how subjective experiences correspond to bodily changes. Research could also extend to aromas passing from the mouth to the nose during eating, and to how brief moments of rest relate to longer-term mood. The study explored the potential for evaluating scent-based self-care and interventions by developing a measurement tool.
References
Hosokawa, Y., Goto, Y., Hoshino, K., & Okada, K. (2025). Development of a self-report scale to assess relaxation effects of flavors and fragrances. Scientific Reports, 15, 27110. DOI: 10.1038/s41598-025-11912-z / Full text. Original article: © The Author(s) 2025, CC BY 4.0.
