Monoterpene Exposure During a Forest Bathing InterventionNCT05316597
Do Terpenes Play a Role in the Stress-reducing Effects of a Forest Bathing Intervention?
A study testing Forest bathing in people with Monoterpene Exposure During a Forest Bathing Intervention, run by University of Washington at 1 site in United States.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Monoterpene Exposure During a Forest Bathing Intervention
- What is being tested?
- Forest bathing
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 43 participants
- Where
- 1 siteUnited States
- Study dates
- 12 Jul 2022to 21 Sep 2023
- Phase
- Interventional
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- 18 years and older
- Non-smoker
- Physically capable of walking for approximately 15-20 min from the study vehicle to the clinic and experimental locations.
Who cannot join
- Pregnancy
- Current or prior diagnosis of neurologic, hypertensive, psychiatric, respiratory disorder, or anosmia/hyposmia
- Some types of medication.
- Olfactory sensitivity threshold (assessed via UPSIT® test kit (Sensonics International, Haddon Heights, NJ)
- At enrollment, participants will complete a baseline survey on demographics, personality traits, and regular nature contact and perceptions. Study staff will also use the clinically-validated UPSIT® test kit (Sensonics International, Haddon Heights, NJ) to evaluate olfactory sensitivity and identify/exclude participants with undiagnosed smell loss.
- Study staff will work with participants to schedule their forest bathing sessions and review instructions on how to prepare (e.g., by avoiding alcohol, marijuana, and certain foods, drinks, and household cleaning products with high terpene concentrations 24 hrs before their session).
Trial locations and contacts
1 site in 1 country.
About this study
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.
Read the detailed description
The investigators will use an individual-level crossover design in which each session is conducted independently and on different days. Participants will be outfitted with a powered air purifying respirator (PAPR) to selectively modulate exposure to a natural suite of forest-derived volatile organic compounds (VOCs) while present in forest environments. Each participant will undergo two forest bathing sessions, one in which VOCs are not filtered (treatment condition), and one in which they are filtered (control condition). Sessions will be separated by a washout period of at least 8 days for each participant, and order will be counterbalanced. The investigators will estimate the average effect of treatment over 40 distinct treatment days against 40 distinct control/filtered days. The power and sample size calculations (N = 40) were determined using previous nature exposure studies of similar cross-over design. The study is adequately powered assuming the conventional targets of α = 0.05 and β = 0.80 with a 10% anticipated dropout rate, and including temperature, wind, and light variability during treatment days.
The specific aim of this project is to 1) assess whether VOC inhalation regulates increases in the high frequency (HF) (ms2) component of heart rate variability (HRV) as the primary outcome (with decreases in blood pressure, heart rate, self-reported stress, and levels of inflammatory cytokines in serum included as secondary outcomes); and 1a) assess the degree of association of absorbed dose of six forest-derived VOCs (i.e., α-pinene, β-pinene, β-myrcene, Δ-3-carene, limonene, β- carophyllene) in serum with these outcomes.
- Being tested
- Forest bathing
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Forest bathingBehavioural
Participants will be seated in a forest environment for an hour-long exposure to the forest
| Study group | Role | What they receive |
|---|---|---|
| Terpenes On | Experimental | Forest bathing intervention with no filtration of terpenes from inhaled air using PAPR with particle-only filter ("terpenes on") Receives: Behavioral: Forest bathing |
| Terpenes Off | Active comparator | Forest bathing intervention with filtration of terpenes from inhaled air using PAPR with activated charcoal filter ("terpenes off") Receives: Behavioral: Forest bathing |
What is being measured
The primary outcome is the main question the study is designed to answer.
Changes in the HF (ms^2) Component of HRV
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)
Measured: 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)).
Baseline HF (ms^2) Component of HRV
Assess whether VOC inhalation regulates psychophysiological outcomes of the terpenes-on vs. terpenes-off sessions.
Ln High Frequency Heart Rate Variability at baseline.
Measured: At baseline (pre-exposure)
Secondary outcomes (22)
Blood Pressure (Diastolic in mmHg)
Assessed using mobile physiology equipment Diastolic blood pressure at T4 (60 minutes of exposure)
Measured: 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)).
Beats Per Minute (BPM)
Assessed using mobile physiology equipment BPM at time point 4 (60 minutes of exposure)
Measured: 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)).
Skin Conductance (μS)
Assessed using mobile physiology equipment Skin conductance levels at time point 2 (20 minutes into exposure)
Measured: 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)).
Self-reported Positive Affect
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
Measured: 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)).
Self-reported Stress
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
Measured: 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)).
Self-reported Negative Affect
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
Measured: 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)).
Levels of CRP
Assessed using blood serum collected via standard clinical methods. CRP levels at time point 4 (60 minutes of exposure).
Measured: 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)).
Levels of Cortisol in Serum (ng/mL)
Assessed using blood serum collected via standard clinical methods Cortisol levels at time point 4 (60 minutes of exposure).
Measured: 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)).
Blood Pressure (Systolic in mmHg)
Assessed using mobile physiology equipment Systolic blood pressure at T4 (60 minutes of exposure)
Measured: 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)).
Level of TNF-alpha
Assessed using blood serum collected via standard clinical methods TNF-alpha levels at time point 4 (60 minutes of exposure).
Measured: 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)).
Levels of Il-6
Assessed using blood serum collected via standard clinical methods IL-6 levels at time point 4 (60 minutes of exposure).
Measured: 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)).
Baseline Blood Pressure (Diastolic in mmHg)
Assessed using mobile physiology equipment Diastolic blood pressure at baseline.
Measured: At baseline (pre-exposure).
Beats Per Minute (BPM)
Assessed using mobile physiology equipment BPM at baseline.
Measured: At baseline (pre-exposure).
Skin Conductance (μS)
Assessed using mobile physiology equipment Skin conductance levels at baseline.
Measured: At baseline (pre-exposure).
Self-reported Positive Affect
Assessed using the shortened Positive and Negative Affect Schedule (PANAS) Positive affect at baseline Higher scale scores are indicative of better outcome Range 5-50
Measured: At baseline (pre-exposure).
Self-reported Stress
Assessed using a single-item self report non-validated scale Self-reported stress at baseline Higher scale score indicative of worse outcome Range 1-5
Measured: At baseline (pre-exposure).
Self-reported Negative Affect
Assessed using the shortened Positive and Negative Affect Schedule (PANAS) Negative affect at baseline Higher score on scale indicative of worse outcome Range 5-50
Measured: At baseline (pre-exposure).
Levels of CRP
Assessed using blood serum collected via standard clinical methods. CRP levels at baseline
Measured: At baseline (pre-exposure).
Levels of Cortisol in Serum (ng/mL)
Assessed using blood serum collected via standard clinical methods Cortisol levels at baseline
Measured: At baseline (pre-exposure).
Blood Pressure (Systolic in mmHg)
Assessed using mobile physiology equipment Systolic blood pressure at baseline
Measured: At baseline (pre-exposure).
Level of TNF-alpha
Assessed using blood serum collected via standard clinical methods TNF-alpha levels at baseline
Measured: At baseline (pre-exposure).
Levels of Il-6
Assessed using blood serum collected via standard clinical methods IL-6 levels at baseline
Measured: At baseline (pre-exposure).
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted7 Apr 2022
- Study start12 Jul 2022
- Primary completion21 Sep 2023
- Study completion21 Sep 2023
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Other trials for Monoterpene Exposure During a Forest Bathing InterventionStudies of the same condition, open and under way.
- More trials run by University of WashingtonThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- Participants are assigned to both arms in random order
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 43 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Washington
- Sponsor type
- University, hospital or other
- Collaborators
- National Center for Complementary and Integrative Health (NCCIH)
- Responsible party
- Principal investigator, Gregory Bratman, University of Washington
- Investigators
- Gregory Bratman, PhD, Principal investigator, University of Washington
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05316597
- Sponsor's protocol ID
- STUDY00013134
- Other IDs
- R21AT011242
- Status last verified
- Aug 2024
- First submitted
- 9 Mar 2022
- Last updated
- 19 Sep 2024
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 19 Sep 2024. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Do Terpenes Play a Role in the Stress-reducing Effects of a Forest Bathing Intervention?
- ClinicalTrials.gov ID
- NCT05316597
- Acronym / sponsor ID
- STUDY00013134
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 43 participants (actual)
- Lead sponsor
- University of WashingtonUniversity, hospital or other
- Collaborators
- National Center for Complementary and Integrative Health (NCCIH)
- Study start
- 12 Jul 2022 (actual)
- Primary completion
- 21 Sep 2023 (actual)
- Study completion
- 21 Sep 2023 (actual)
- First posted
- 7 Apr 2022 (actual)
- Results
- Posted 19 Sep 2024
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed description
The investigators will use an individual-level crossover design in which each session is conducted independently and on different days. Participants will be outfitted with a powered air purifying respirator (PAPR) to selectively modulate exposure to a natural suite of forest-derived volatile organic compounds (VOCs) while present in forest environments. Each participant will undergo two forest bathing sessions, one in which VOCs are not filtered (treatment condition), and one in which they are filtered (control condition). Sessions will be separated by a washout period of at least 8 days for each participant, and order will be counterbalanced. The investigators will estimate the average effect of treatment over 40 distinct treatment days against 40 distinct control/filtered days. The power and sample size calculations (N = 40) were determined using previous nature exposure studies of similar cross-over design. The study is adequately powered assuming the conventional targets of α = 0.05 and β = 0.80 with a 10% anticipated dropout rate, and including temperature, wind, and light variability during treatment days.
The specific aim of this project is to 1) assess whether VOC inhalation regulates increases in the high frequency (HF) (ms2) component of heart rate variability (HRV) as the primary outcome (with decreases in blood pressure, heart rate, self-reported stress, and levels of inflammatory cytokines in serum included as secondary outcomes); and 1a) assess the degree of association of absorbed dose of six forest-derived VOCs (i.e., α-pinene, β-pinene, β-myrcene, Δ-3-carene, limonene, β- carophyllene) in serum with these outcomes.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind (participant, investigator)
- Number of arms
- 2
- Model description
- Participants are assigned to both arms in random order
| Arm | Type | Receives |
|---|---|---|
| Terpenes On | Experimental | Behavioral: Forest bathingForest bathing intervention with no filtration of terpenes from inhaled air using PAPR with particle-only filter ("terpenes on") |
| Terpenes Off | Active comparator | Behavioral: Forest bathingForest bathing intervention with filtration of terpenes from inhaled air using PAPR with activated charcoal filter ("terpenes off") |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (3 listed)
- 18 years and older
- Non-smoker
- Physically capable of walking for approximately 15-20 min from the study vehicle to the clinic and experimental locations.
Key exclusion criteria (6 listed)
- Pregnancy
- Current or prior diagnosis of neurologic, hypertensive, psychiatric, respiratory disorder, or anosmia/hyposmia
- Some types of medication.
- Olfactory sensitivity threshold (assessed via UPSIT® test kit (Sensonics International, Haddon Heights, NJ)
- At enrollment, participants will complete a baseline survey on demographics, personality traits, and regular nature contact and perceptions. Study staff will also use the clinically-validated UPSIT® test kit (Sensonics International, Haddon Heights, NJ) to evaluate olfactory sensitivity and identify/exclude participants with undiagnosed smell loss.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Forest bathingParticipants will be seated in a forest environment for an hour-long exposure to the forest | Behavioural | Terpenes Off, Terpenes On |
Primary outcome
Changes in the HF (ms^2) Component of HRV
Time frame: 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)
Baseline HF (ms^2) Component of HRV
Time frame: At baseline (pre-exposure)
Assess whether VOC inhalation regulates psychophysiological outcomes of the terpenes-on vs. terpenes-off sessions. Ln High Frequency Heart Rate Variability at baseline.
22 secondary outcomes
Blood Pressure (Diastolic in mmHg)
Time frame: 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)).
Beats Per Minute (BPM)
Time frame: 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)).
Skin Conductance (μS)
Time frame: 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)).
Self-reported Positive Affect
Time frame: 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)).
Self-reported Stress
Time frame: 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)).
Self-reported Negative Affect
Time frame: 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)).
Levels of CRP
Time frame: 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)).
Levels of Cortisol in Serum (ng/mL)
Time frame: 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)).
Blood Pressure (Systolic in mmHg)
Time frame: 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)).
Level of TNF-alpha
Time frame: 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)).
Levels of Il-6
Time frame: 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)).
Baseline Blood Pressure (Diastolic in mmHg)
Time frame: At baseline (pre-exposure).
Beats Per Minute (BPM)
Time frame: At baseline (pre-exposure).
Skin Conductance (μS)
Time frame: At baseline (pre-exposure).
Self-reported Positive Affect
Time frame: At baseline (pre-exposure).
Self-reported Stress
Time frame: At baseline (pre-exposure).
Self-reported Negative Affect
Time frame: At baseline (pre-exposure).
Levels of CRP
Time frame: At baseline (pre-exposure).
Levels of Cortisol in Serum (ng/mL)
Time frame: At baseline (pre-exposure).
Blood Pressure (Systolic in mmHg)
Time frame: At baseline (pre-exposure).
Level of TNF-alpha
Time frame: At baseline (pre-exposure).
Levels of Il-6
Time frame: At baseline (pre-exposure).
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 19 Sep 2024.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Gregory Bratman, PhD principal investigator
University of Washington
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Forest bathing in people with Monoterpene Exposure During a Forest Bathing Intervention, run by University of Washington at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 6 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 19 Sep 2024. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
Yes. Results are posted in the registry (first posted 19 Sep 2024). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Changes in the HF (ms^2) Component of HRV (time frame: 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)).). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 19 Sep 2024.