Forest Therapy and Mindfulness for Highly Sensitive Persons (HSP-FOREST)

January 18, 2026 updated by: IFM International Forest Medicine

Forest Therapy and Mindfulness in Highly Sensitive Persons (HSP): A Multicenter Randomized Interventional Study Over Approximately 22 Weeks

This randomized, multicenter interventional study evaluates a combined forest therapy (shinrin-yoku) and mindfulness-based program in adults with high sensory-processing sensitivity confirmed using a validated instrument. Participants are randomized (1:1) to either a forest-based intervention or an active indoor sensory control condition. The intervention is delivered over approximately 22 weeks according to a predefined protocol, with assessments conducted at baseline and at the end of the intervention.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

This is a multicenter, randomized, parallel-group interventional study in adults with high sensory-processing sensitivity confirmed using a validated instrument. Participants are randomized 1:1 to one of two study arms at study entry and remain in their assigned group for the duration of the study.

Intervention delivery is standardized across participating sites through facilitator training and a predefined session manual. The experimental arm consists of structured sessions conducted in forest environments and includes guided walking, mindfulness-based practices, and structured sensory awareness activities, with facilitated group reflection. The active comparator arm consists of structured indoor group activities designed to match the experimental arm in duration, group interaction, and facilitator contact, without exposure to forest or outdoor natural environments.

Study procedures and assessment schedules are predefined in the protocol and implemented in accordance with applicable ethical requirements and Good Clinical Practice guidelines.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
310

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Spain
    • Andalusia
      • Ronda, Andalusia, Spain, 29492
        • IFM International Forest Medicine
      • Ronda, Andalusia, Spain, 29492
        • Sessions conducted in natural forest settings within the Serranía de Ronda, specifically the Valle del Genal area

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Age 18 to 65 years
  • High sensory-processing sensitivity confirmed using a validated instrument (e.g., HSPS/Aron scale)
  • Able to perform moderate physical activity (e.g., walking)
  • Able to provide written informed consent

Exclusion Criteria:

  • Severe psychiatric disorder or acute clinical instability
  • Medical condition contraindicating moderate physical activity
  • Use of medications with strong autonomic or neuroendocrine effects (e.g., high-dose systemic corticosteroids; selected beta-blockers)
  • Recent participation in a structured mindfulness or forest-therapy program
  • Pregnancy or unstable medical condition

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Forest Therapy + Mindfulness + Psychotherapy
Participants will undergo an approximately 22-week program with 4.5 hours weekly in forest settings. Sessions include a guided forest walk, mindfulness meditation, structured sensory awareness exercises, facilitated group reflection, and a brief psychotherapeutic component focused on emotional processing and cognitive regulation. Intervention delivery is standardized through facilitator training and a predefined session manual.
Behavioral: Forest Therapy + Mindfulness + Psychotherapy

Participants will undergo a approximately 22-week program with 4.5 hours weekly in forest settings. Each session includes:

A 2-hour guided walk with scheduled rest/hydration breaks

Mindfulness meditation (20-30 minutes)

Discussion/reflection segment (~20 minutes) for participants to express sensations, experiences, or doubts

A psychotherapeutic component focused on emotional processing and cognitive regulation

Sensory observation (5-10 minutes) of forest stimuli (olfactory, auditory, tactile, visual)

Post-session journaling capturing emotional and sensory feedback

Monitoring of environmental parameters (temperature, humidity, wind, estimated phytoncide levels)

Standardized facilitator training and session protocols to ensure consistency across sites

This protocol is distinguished by integrating forest immersion, mindfulness, psychotherapy, and sensory training in a unified intervention tailored for Highly Sensitive Persons (HSP).
Active Comparator: Indoor Sensory Control (Art and Aromatherapy)
Structured indoor sensory-based group sessions delivered weekly over approximately 22 weeks. Sessions are designed to match the experimental intervention in duration, structure, facilitator contact, and social interaction, without exposure to forest or outdoor natural environments. Activities include creative tasks, guided aromatherapy, sensory-focused exercises, and facilitated group discussion according to a predefined protocol.
Behavioral: Behavioral: Indoor Sensory Control (Art and Aromatherapy)
Structured indoor sensory-based group sessions delivered weekly over approximately 22 weeks. Activities include creative tasks, guided aromatherapy, and sensory-focused exercises conducted in indoor, non-forest environments. Sessions are designed to match the experimental intervention in duration, structure, facilitator contact, and social interaction, according to a predefined protocol.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Change in Perceived Stress Score (PSS-10) From Baseline to End of Intervention
Time Frame: Baseline to end of intervention (approximately 22 weeks)
Measure the difference in total score on the Perceived Stress Scale (PSS-10) between baseline and the end of the intervention. PSS-10 comprises 10 items scored 0-40, with higher scores indicating greater perceived stress.
Baseline to end of intervention (approximately 22 weeks)

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change in Psychological Well-Being Score (WHO-5) From Baseline to End of Intervention
Time Frame: Baseline to end of intervention (approximately 22 weeks)
Measure the difference in total score on the WHO-5 Well-Being Index between baseline and the end of the intervention. WHO-5 comprises 5 items scored 0-25, with higher scores indicating better well-being.
Baseline to end of intervention (approximately 22 weeks)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
IFM International Forest Medicine

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Ana I Sánchez Hdz, IFM International Forest Medicine

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

  • Sánchez Hdz, Ana I. Forest Therapy and Mindfulness in Highly Sensitive Persons (HSP): Confirmatory Evidence from a Multicenter Randomized Controlled Trial with 6-Month Follow-up. Zenodo. DOI: 10.5281/zenodo.17361382. Available at: https://zenodo.org/records/17361382

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
May 1, 2025

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
October 3, 2025

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
October 3, 2025

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
December 12, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 18, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
January 26, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
January 26, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 18, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
January 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • HSP-FOREST-2025-RTC-C
  • HSP-FOREST-2025-C (Registry Identifier: ClinicalTrials.gov)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

De-identified individual participant data supporting publications arising from this study will be shared with qualified researchers beginning 6 to 36 months after publication.

IPD Sharing Time Frame

Beginning 6 months after publication and available for up to 36 months.

IPD Sharing Access Criteria

Access will be granted to qualified researchers upon reasonable request, subject to approval by the responsible ethics committee and execution of a data use agreement. Requests must include a research proposal and analysis plan.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL

Study Data/Documents

  1. Study Protocol
    Information identifier: ZENODO17361382
    Information comments: Access via the URL provided (Zenodo record)

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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