Imagine smelling a forest-like scent while listening to audio that directs attention to breathing and mental imagery. Is this combination more calming than a short break alone? And after repeated sessions, could the scent alone bring back the same calmness?
A study that randomized 504 people, published in 2026, investigated these two questions. After four weeks, the scent-plus-hypnosis group reported greater calmness than the rest group. However, the effect of adding scent itself and the proposed mechanism by which scent alone might recall calmness require careful interpretation.
- Combining scent with short breaks in everyday life
- 504 participants were randomized into four groups and compared over four weeks
- Calmness increased in the combined group, but the result has a limited scope
- Can scent alone bring calmness back?
- The advantages and limitations of a home-based program
- Summary
Combining scent with short breaks in everyday life
The authors aimed to test a relaxation method that could fit easily into daily life and be accessed from home. They developed an online program combining audio-guided hypnosis with a forest-associated essential-oil spray to investigate whether engaging multiple senses could promote calmness.
Participants were adults aged 18–65 living in Germany. People reporting a current or past mental illness or receiving psychotherapy or hypnotherapy, among others, were excluded. The study therefore cannot be read as a test of treatment efficacy for patients with anxiety disorders or depression.
504 participants were randomized into four groups and compared over four weeks
Participants were randomized to scent plus hypnosis audio (128), hypnosis audio alone (121), scent alone (131), or minimal rest (124). Baseline assessments were completed by 485 people, and four-week assessments by 383. The figure 504 refers to the number randomized, not the number who completed every assessment.
The combined group sprayed a commercial forest-associated product using Swiss pine (Pinus cembra) into the surrounding air once or twice and listened to the audio. The recordings included prompts for slow breathing and mental imagery, lasting about 22 minutes initially and about 11 minutes thereafter. The hypnosis-only group followed the same content and schedule without scent. Sessions were generally offered every 48 hours.
The scent-only group received the same spray and a five-minute recording with brief instructions to adopt a comfortable posture and attend to the scent. The rest group used the same five-minute recording without scent. Thus, “scent alone” did not mean simply encountering a scent at random in everyday life. Sessions also differed in length between the hypnosis groups and the rest group.
Calmness increased in the combined group, but the result has a limited scope
The primary outcome was self-reported calmness measured by questionnaire. In an analysis adjusting for baseline scores, the combined group scored about 2.08 points higher than the rest group at four weeks, with an effect size of d = 0.38. The p-value adjusted for multiple comparisons was 0.044, below the study’s 0.05 threshold.
The hypnosis-only result deserves particular attention. Its difference from rest was about 1.80 points, with an unadjusted p-value of 0.024, but an adjusted value of 0.064. Some passages in the abstract and main text describe both groups as significant. Judged by the adjusted figures in the primary-results table, however, the hypnosis-only comparison does not meet the 0.05 threshold.
Moreover, significance for the combination but not for hypnosis alone does not establish that adding scent increased the effect. That would require testing the difference between the combined and hypnosis-only groups directly. The primary-results table reports each group’s comparison with rest.
The authors noted the slightly better numerical results in the scent-added group and discussed a possible additional benefit. That interpretation should be distinguished from an established scent-specific incremental effect. Neither the combined nor hypnosis-only group clearly differed from rest on the PSS-10 measure of perceived stress. The calmness result cannot simply be extended to broad improvements in mental or physical health.
Can scent alone bring calmness back?
The second aim was to test conditioning: the idea that repeatedly pairing the same scent with a calming experience might eventually allow the scent alone to evoke calmness.
In week five, both the original combined group and the original scent-only group used only the scent and a brief five-minute instructional recording. No clear difference emerged between them after accounting for immediately preceding calmness scores. Under these conditions, there was no evidence that people previously exposed to scent with hypnosis became more relaxed from the scent alone.
The authors identified the number of pairings, the scent’s personal meaning, and how it reached participants at home as questions for further research. These are possible explanations, not confirmation that conditioning would occur with a preferred scent or more sessions.
The advantages and limitations of a home-based program
A distinctive feature was testing a four-week program embedded in daily life without requiring laboratory visits. However, outcomes were self-reported, and participants could not be fully blinded to scent presence. Differences in expectations or engagement may have affected the results. The study also did not measure heart-rate variability, salivary cortisol, or other physiological mechanisms.
More than 80% of participants were women, and about one fifth stopped responding between baseline and week four. The researchers also statistically imputed missing data for an analysis of all 504 participants, but that approach depends on assumptions about how data went missing. The experience of completers must be distinguished from effects in a broader population of users.
The authors concluded that brief online interventions may support everyday calmness and that improving scent selection and delivery is worthwhile. PRIMAVERA LIFE provided the essential-oil spray free of charge; the paper states that the company had no role in study design, conduct, analysis, or interpretation.
Summary
In this study, a four-week program combining forest-associated scent with hypnosis audio improved subjective calmness compared with brief rest alone. Its contribution lies in testing online relaxation that can be incorporated into everyday life.
However, a distinct benefit from adding scent was not established, and week five did not confirm conditioning that allowed scent alone to bring calmness back. The authors recommend further testing of brief digital interventions with improvements in personalized scent selection and delivery.
References
Authors: Steven Ngandeu Schepanski, Martin Bogdanski, Katja Karolina Siegfried, Steffen Schulz, Judith Czakert, Farid Kandil, Michael Teut, Julia Siewert, Georg Seifert
Article: Promoting relaxation through essential oil-enhanced digital hypnotherapy: A randomized controlled trial
Journal: Psychological Medicine 56, e80 (2026)
DOI: 10.1017/S0033291726103778
Full original article: Open PDF at Cambridge University Press
Rights: The original article is published under CC BY 4.0.
