This study is a non-clinical substudy conducted within the DESTRESS research program (NCT05036538), which investigates the effects of relaxation interventions on physiological and psychological parameters. While the main DESTRESS trial focuses on cardiac surgical patients, this additional study arm examines the same interventions in a non-clinical adult population under controlled conditions, independent of disease-, surgery-, or medication-related influences.

Participants are randomly assigned to one of several experimental conditions and take part in a single approximately 30-minute session. Depending on group allocation, the session may include exposure to natural soundscapes, natural soundscapes combined with binaural beats, virtual reality-based natural environments, virtual reality combined with binaural beats, or a control condition without a relaxation intervention.

The primary aim of the DESTUD-Study is to assess the feasibility and potential stress-reducing effects of these non-pharmacological relaxation approaches in a non-clinical setting and to support the interpretation of findings from the clinical DESTRESS trial. Physiological responses, including heart rate variability and electrodermal activity, as well as self-reported stress measures, are collected before, during and after the conditions.

This study is conducted as a non-clinical substudy within the DESTRESS research program (Decreasing preoperative stress to prevent postoperative delirium and postoperative cognitive decline in cardiac surgical patients: A randomized controlled trial on relaxation interventions via virtual reality and binaural beats; NCT05036538). In contrast to the main clinical trial, which investigates cardiac surgical patients, this study focuses on non-clinical adult participants who are not undergoing medical or surgical treatment and are not enrolled as patients of the Kerckhoff-Clinic Bad Nauheim (Germany).

The purpose of this substudy is to examine the effects of relaxation interventions under controlled conditions, independent of disease-related, perioperative, or pharmacological confounding factors. The results are intended to provide a reference framework for interpreting and contextualizing findings from the clinical DESTRESS trial.

Participants are randomly assigned to one of five experimental conditions: (1) natural soundscapes, (2) natural soundscapes combined with binaural beats, (3) virtual reality-based natural environments, (4) virtual reality-based natural environments combined with binaural beats, or (5) a control condition without any relaxation intervention. Each participant completes a single session lasting approximately 30 minutes.

During the intervention or control condition, physiological parameters, including heart rate variability and electrodermal activity, are continuously recorded using non-invasive sensors. Neurocognition and subjective stress levels are assessed using standardized tests and self-report questionnaires administered before and after the session.

This study aims to evaluate the feasibility, acceptability, and preliminary efficacy of virtual reality- and audio-based relaxation interventions in a non-clinical population. The findings are expected to contribute to a better understanding of the mechanisms and generalizability of stress-reduction approaches and to inform the interpretation of outcomes in the overarching DESTRESS research program.

Inclusion Criteria:

1. Adults aged 18 years or older 2. Ability to understand study procedures and provide written informed consent 3. Sufficient proficiency in the German language to complete questionnaires and follow study instructions 4. Willingness to participate in a single approximately 60-minute study session

Exclusion Criteria:

1. Current or history of neurological or psychiatric disorders that may interfere with data collection (e.g., dementia, major depressive disorder, stroke, epilepsy) 2. Severe visual or hearing impairments that would limit the use of virtual reality equipment or headphones 3. History of adverse reactions to virtual reality

This is an open-label study. Due to the nature of the interventions, participants and investigators are not blinded to group assignment.