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

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: Completed
• Conditions: Complementary Therapies; Preventive Medicine; Mindfulness; Stress (Psychology); Mind-Body Therapies; Well-Being, Psychological
• Intervention / Treatment: Behavioral: Forest Therapy + Mindfulness + Psychotherapy; Behavioral: Behavioral: Indoor Sensory Control (Art and Aromatherapy)

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: Interventional
• Enrollment (Actual): 310
• Phase: Not Applicable

Contacts and Locations

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

Eligibility Criteria

• 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

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
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

Outcome Measure	Measure Description	Time Frame
Change in Perceived Stress Score (PSS-10) From Baseline to End of Intervention	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

Outcome Measure	Measure Description	Time Frame
Change in Psychological Well-Being Score (WHO-5) From Baseline to End of Intervention	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

• Sponsor: IFM International Forest Medicine
• Investigators: Principal Investigator: Ana I Sánchez Hdz, IFM International Forest Medicine

Publications and helpful links

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

• Forest Therapy and Mindfulness for Stress Reduction and Well-being in Highly Sensitive Persons (Pilot RCT)" (HSP-FOREST)

Study record dates

Study Major Dates

• Study Start (Actual): May 1, 2025
• Primary Completion (Actual): October 3, 2025
• Study Completion (Actual): October 3, 2025

Study Registration Dates

• First Submitted: December 12, 2025
• First Submitted That Met QC Criteria: January 18, 2026
• First Posted (Actual): January 26, 2026

Study Record Updates

• Last Update Posted (Actual): January 26, 2026
• Last Update Submitted That Met QC Criteria: January 18, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Keywords: Mental Health; Mindfulness; Stress reduction; Forest Therapy; Forest Bathing; Shinrin Yoku; Highly Sensitive Person (HSP); Forest Medicine
• Additional Relevant MeSH Terms: Behavior; Personal Satisfaction; Psychological Well-Being; Investigative Techniques; Therapeutics; Mind-Body Therapies; Complementary Therapies; Behavior Therapy; Behavioral Disciplines and Activities; Cognitive Behavioral Therapy; Reproductive Techniques; Sensory Art Therapies; Phytotherapy; Relaxation Therapy; Mindfulness; Psychotherapy; Aromatherapy; Forest Therapy; Reproductive Techniques, Assisted
• Other Study ID 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