NCT05316597

Do Terpenes Play a Role in the Stress-reducing Effects of a Forest Bathing Intervention?

Completed NA Results posted Last updated 19 September 2024

What this trial tests

NA trial testing Forest bathing in Monoterpene Exposure During a Forest Bathing Intervention in 43 participants. Completed in 21 September 2023.

Timeline

12 July 2022

Primary endpoint
21 September 2023

21 September 2023

Quick facts

Lead sponsor	University of Washington
Phase	NA
Status	Completed
Study type	INTERVENTIONAL
Allocation	randomized
Design	crossover
Masking	double
Primary purpose	prevention
Enrollment	43
Start date	12 July 2022
Primary completion	21 September 2023
Estimated completion	21 September 2023
Sites	1 location across United States

Drugs / interventions tested

• Forest bathing

Conditions studied

• Monoterpene Exposure During a Forest Bathing Intervention — all drugs for Monoterpene Exposure During a Forest Bathing Intervention →

Sponsor

University of Washington

Who can join

18 and older, any sex, with Monoterpene Exposure During a Forest Bathing Intervention. Patients with the condition only — healthy volunteers not accepted.

Results — posted to ClinicalTrials.gov

Per-arm endpoint measurements with 95% confidence intervals where reported. Source: trial results section.

Changes in the HF (ms^2) Component of HRV Primary · At time point 2 (20 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).

Assess whether VOC inhalation regulates psychophysiological outcomes of the terpenes-on vs. terpenes-off sessions. Ln High Frequency Heart Rate Variability at T2 (20 minutes into duration of exposure for each session)

Group	Value	95% CI
Terpenes On	6.65	± 1.33
Terpenes Off	6.48	± 1.14

Blood Pressure (Diastolic in mmHg) Secondary · At time point 4 (60 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).

Assessed using mobile physiology equipment Diastolic blood pressure at T4 (60 minutes of exposure)

Group	Value	95% CI
Terpenes On	75.4	± 9.86
Terpenes Off	73.2	± 11.1

Beats Per Minute (BPM) Secondary · At time point 4 (60 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).

Assessed using mobile physiology equipment BPM at time point 4 (60 minutes of exposure)

Group	Value	95% CI
Terpenes On	61.4	± 11.9
Terpenes Off	63.0	± 13.7

Skin Conductance (μS) Secondary · At time point 2 (20 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).

Assessed using mobile physiology equipment Skin conductance levels at time point 2 (20 minutes into exposure)

Group	Value	95% CI
Terpenes On	3.28	± 3.76
Terpenes Off	4.14	± 5.94

Self-reported Positive Affect Secondary · At time point 2 (20 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).

Assessed using the shortened Positive and Negative Affect Schedule (PANAS) Positive affect at time point 2 (20 minutes of exposure) Higher scale scores are indicative of better outcome Range 5-50

Group	Value	95% CI
Terpenes On	12.1	± 4.00
Terpenes Off	11.3	± 4.38

Self-reported Stress Secondary · At time point 2 (20 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).

Assessed using a single-item self report non-validated scale Self-reported stress at time point 2 (20 minutes of exposure) Higher scale score indicative of worse outcome Range 1-5

Group	Value	95% CI
Terpenes On	1.09	± 0.390
Terpenes Off	1.17	± 0.447

Self-reported Negative Affect Secondary · At time point 2 (20 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).

Assessed using the shortened Positive and Negative Affect Schedule (PANAS) Negative affect at time point 2 (20 minutes of exposure) Higher score on scale indicative of worse outcome Range 5-50

Group	Value	95% CI
Terpenes On	5.13	± 0.421
Terpenes Off	5.31	± 0.749

Levels of CRP Secondary · At time point 4 (60 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).

Assessed using blood serum collected via standard clinical methods. CRP levels at time point 4 (60 minutes of exposure).

Group	Value	95% CI
Terpenes On	9.99	± 7.83
Terpenes Off	13.4	± 12.5

Levels of Cortisol in Serum (ng/mL) Secondary · At time point 4 (60 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).

Assessed using blood serum collected via standard clinical methods Cortisol levels at time point 4 (60 minutes of exposure).

Group	Value	95% CI
Terpenes On	98.6	± 43.6
Terpenes Off	109.0	± 60.0

Blood Pressure (Systolic in mmHg) Secondary · At time point 4 (60 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).

Assessed using mobile physiology equipment Systolic blood pressure at T4 (60 minutes of exposure)

Group	Value	95% CI
Terpenes On	123	± 16.9
Terpenes Off	121	± 14.0

Level of TNF-alpha Secondary · At time point 4 (60 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).

Assessed using blood serum collected via standard clinical methods TNF-alpha levels at time point 4 (60 minutes of exposure).

Group	Value	95% CI
Terpenes On	3.80	± 2.71
Terpenes Off	4.27	± 2.84

Levels of Il-6 Secondary · At time point 4 (60 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).

Assessed using blood serum collected via standard clinical methods IL-6 levels at time point 4 (60 minutes of exposure).

Group	Value	95% CI
Terpenes On	0.547	± 0.609
Terpenes Off	0.763	± 0.820

Sponsor's own description

This pilot study evaluates the role terpenes play in the stress-reducing effects of a forest bathing intervention. Participants will participate in two interventions in random order: 1) terpene exposure and 2) no terpene exposure.

Publications & conference data

1 peer-reviewed publication reference this trial (live from Europe PMC):

1. Forest terpenes and stress: Examining the associations of filtered vs. non-filtered air in a real-life natural environment.
   Levy CM, Riederer AM, Simpson CD, Gassett AJ, et al · · 2025 · cited 1× · PMID 40147520 · DOI 10.1016/j.envres.2025.121482