Cold Water and Decision-Making (CoVa)

Voluntary Cold-Water Immersion Effects on Value-Based Choice

The behavioral within-subject cross-over design study "CoVa" aims to investigate the effect of a short-term full-body cold-water immersion vs. warm-water immersion control on value-based choice, psychological well-being, and peripheral physiology.

Study Overview

• Status: Recruiting
• Conditions: Quality of Life; Stress; Behavior; Psychological Wellbeing
• Intervention / Treatment: Behavioral: Cold-water immersion; Behavioral: Warm-water immersion (Control)

Detailed Description

This randomized within-subject cross-over design behavioral study in cognitive neuroscience will employ an acute peripheral physiological intervention, i.e., a 10-minute full-body cold-water (10-16°C) immersion vs. a control condition (10 min @ 30- 36°C water) on two visits separated by approx. 30 days.

Forty eligible female and male participants will be subject to a head-out full-body cold-water immersion or a warm-water condition (control) on two visits. Participants will perform resting-state and task-based non-invasive electrophysiological recordings of the heart, pulse, respiration, skin conductance, and pupil, will undergo thermographic imaging, pre- and post-immersion blood sampling (4 time points), engage in two computer-based decision-making tasks (reinforcement learning task, risk decision-making task), a brief food choice task, and receive a battery of psychometric questionnaires. The visits are separated by approximately 30 days and do not differ in their timeline except for the primary intervention, i.e., cold vs warm-water immersion, and the medical screening on visit 1.

• Study Type: Interventional
• Enrollment (Estimated): 40
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Trust Centre of the Human Study Centre Recruitment Officer; Phone Number: +4933200 882753; Email: CoVa-Studie@dife.de
• Study Contact Backup: Name: Mine Schmidt; Phone Number: +4933200 882518; Email: mine.schmidt@dife.de

Study Locations

• Germany
  • Nuthetal, Germany
    • Recruiting
    • German Institute of Human Nutrition Potsdam-Rehbruecke
    • Contact: Recruitment Officer; Phone Number: +4933200 882753; Email: CoVa-Studie@dife.de

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• 18-40 years of age
• Consent to participate
• Fluency in German
• Physically and mentally healthy
• BMI 18-30 kg/m2
• Normal day-night rhythm

Exclusion Criteria:

• Raynaud syndrome
• Cold urticaria
• High resting heart rate (>160 beats per minute)
• Acute infection

• Diagnosed current or former illnesses of

  • Brain and mind
  • Heart and blood circulation
  • Gastrointestinal system
  • Endocrine system
  • Other serious past or present medical conditions
• Wearing of medical devices (e.g., pacemaker)
• Fear of blood, needles, or phlebotomy
• Allergies to plasters, gels, and other medical equipment
• Allergies to commercially available liquid meals (e.g., shakes, yfood Labs GmbH)
• Recurrent intake of medication which affect metabolism
• Regular nicotine consumption (e.g., vaping, cigarettes)
• Excessive alcohol consumption (>14 servings/week)
• Recent illegal drug consumption (within 2 weeks prior)
• Strong mental or physical stress
• Excessive exercise (>2 h high-intensity exercise/day)
• Pregnancy or breastfeeding
• Inability to wear skin-exposing swimwear, e.g., for religious reasons
• Affinity for winter swimming, cryotherapy, breathwork (>3 times/year)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Cold-water immersion	Behavioral: Cold-water immersion; Single 10-minute acute full-body head-out single arm-out cold-water immersion at 10-16°C on the experimental day
Experimental: Warm-water immersion (Control)	Behavioral: Warm-water immersion (Control); Single 10-minute acute full-body head-out single arm-out cold-water immersion at 30-36°C on the experimental day

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Risk propensity	Risk propensity, i.e., the ratio between risky and non-risky choices for each monetary value as measured in the risk decision-making task in the cold-water vs warm-water condition as described in Liu et al. (2021)	On day 1 and after 30 days
Behavioral range adaptation	Participants will perform a computer-based reinforcement learning task described in Gueguen et al. (2024) to assess reward sensitivity in different monetary contexts. Behavioral range adaptation, which reflects value range-dependent, relative reward valuation, may be altered if reward processing itself is changed through a potent shift in the physiological state. To test whether reward processing is altered after cold vs warm water exposure, the extent to which range adaptation and reference-point centering occurs will be quantified using computational modeling methods.	On day 1 and after 30 days
Food choice	Participants will be provided an ad libitum restaurant-like breakfast meal during which they can order various food items (e.g., bread, yogurts, cookies) in the desired amount. The ingested food type, nutritional value, and amount will be quantified to assess food preference after cold vs warm water exposure by linking the consumed food with a standardized food database (German Nutrient Database, Bundeslebensmittelschlüssel).	On day 1 and after 30 days
Heart-rate variability	Task-based and resting-state heart-rate variability, measured with a three-point electrocardiogram (ECG)	On day 1 and after 30 days
Heart rate	Task-based and resting-state heart rate, measured with ECG	On day 1 and after 30 days
Respiration rate	Task-based and resting-state respiration rate, measured via a respiration belt	On day 1 and after 30 days
Relative amplitude of the respiratory signal	Task-based and resting-state relative respiratory amplitude, measured via a respiratory belt	On day 1 and after 30 days
Event-related skin conductance responses	Phasic electrodermal activity, measured via electrodermal activity (EDA) electrodes	On day 1 and after 30 days
Tonic skin conductance	Tonic task-based and resting-state electrodermal activity, measured with EDA electrodes	On day 1 and after 30 days
Pupil dilation	Task-based and resting-state pupil dilation, measured via eye-tracking	On day 1 and after 30 days
Skin temperature	Thermographic imaging of the face, full-body, supraclavicular, and scapular area using a thermal camera pre-, during, and post-immersion	On day 1 and after 30 days
Plasma concentration of large neutral amino acids	Large neutral amino acid (LNAA) plasma concentration will be assessed via blood sampling at 4 time points (pre-immersion to 120 min post-immersion)	On day 1 and after 30 days
Plasma concentration of catecholamines	Catecholamines via blood sampling at 4 time points (pre-immersion to 120 min post-immersion)	On day 1 and after 30 days
Plasma concentration of cortisol	Cortisol via blood sampling at 4 time points (pre-immersion to 120 min post-immersion)	On day 1 and after 30 days
Identification of epigenetic markers associated with acute cold exposure	Epigenetic markers (micro-RNA) via blood sampling at 4 time points (pre-immersion to 120 min post-immersion)	On day 1 and after 30 days
Perceived control	Psychological changes in perceived control, measured semi-continuously via self-reports throughout the experimental day. Measures range from 0% (not at all) to 100% (very much) with 100% indicating high perceived control.	On day 1 and after 30 days
Perceived freedom	Psychological changes in perceived freedom, measured semi-continuously via self-reports throughout the experimental day. Measures range from 0% (not at all) to 100% (very much) with 100% indicating high perceived freedom.	On day 1 and after 30 days
Perceived stress	Psychological changes in perceived stress, measured semi-continuously via self-reports throughout the experimental day. Measures range from 0% (not at all) to 100% (very much) with 100% indicating high perceived stress.	On day 1 and after 30 days
State of flow	Psychological changes in perceived state of flow, measured semi-continuously via self-reports throughout the experimental day. Measures range from 0% (not at all) to 100% (very much) with 100% indicating a high state of flow.	On day 1 and after 30 days
Self-efficacy	Psychological changes in self-efficacy, measured semi-continuously via self-reports throughout the experimental day. Measures range from 0% (not at all) to 100% (very much) with 100% indicating high self-efficacy.	On day 1 and after 30 days
Perceived pain	Psychological changes in perceived pain, measured semi-continuously via self-reports throughout the experimental day. Measures range from 0% (not at all) to 100% (very much) with 100% indicating high perceived pain.	On day 1 and after 30 days
Emotions	Psychological changes in emotions and their bodily origins, measured via self-reports pre- and post-immersion. Measures will be drawn on a virtual body using an adapted version of the Nummenmaa et al. (2014) emBODY tool with red color indicating increased perception and blue indicating decreased perception.	On day 1 and after 30 days
Positive affect and negative affect questionnaire	Psychological changes in affect, measured semi-continuously via the Positive Affect Negative Affect (PANAS) questionnaire to be filled out pre- and post-immersion. Measures for each item range from 1 (not at all) to 5 (very much) with 5 indicating the highest feeling perceived at the moment.	On day 1 and after 30 days

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Trait autonomy questionnaire	Trait autonomy is assessed via the Basic Psychological Need Satisfaction and Frustration Scale (BPNSFS). Measures range from 1 (not at all true) to 5 (totally true) with 5 indicating the highest score.	On day 1 and after 30 days
Emotion regulation questionnaire	Emotion regulation, assessed via the Emotion Regulation Questionnaire (ERQ). Measures range from 1 (not at all true) to 7 (totally true) with 7 indicating the highest score.	On day 1 and after 30 days
Causality orientation questionnaire	Causality orientation, assessed via the General Causality Orientations Scale (GCOS). Measures range from 1 (very unlikely) to 6 (very likely) with 6 indicating the highest probability of responding as the item describes in the vignette scenario.	On day 1 and after 30 days
Delay discounting questionnaire	Delay discounting is assessed via the Delay Discounting Test by Kirby. Response options to each item are binary with one option corresponding to an immediate reward (e.g., 14 EUR today) and the second option corresponding to a higher but delayed reward (e.g., 19 EUR in 60 days).	On day 1 and after 30 days
Interoceptive awareness questionnaire	Interoceptive awareness, assessed via the Multidimensional Assessment of Interoceptive Awareness (MAIA) questionnaire. Measures range from 0 (never) to 5 (always) with 5 indicating the highest response.	On day 1 and after 30 days
Generalized self-efficacy questionnaire	Generalized self-efficacy, assessed via the Self-Efficacy Scale (SWE). Measures range from "not at all true", "hardly true", "moderately true" and "exactly true". A higher score, indicated by a preference for "exactly true", indicated more self-efficacy.	On day 1 and after 30 days
Trait and state anxiety questionnaire	Trait and state anxiety, assessed via the State-Trait Anxiety Inventory (STAI-S and STAI-T). State anxiety is assessed on a scale from 1 (not at all) to 8 (very much) with a higher score indicating high state anxiety. Trait anxiety is assessed on a scale from 0 (almost never) to 3 (almost always) with a higher score indicating high trait anxiety.	On day 1 and after 30 days
Well-being questionnaire	Psychological well-being is assessed via the short version of the Warwick-Edinburgh Mental Well-Being Scale (SWEMWBS). Responses range from "never" to "always" on a 5-point scale with a high score indicating higher mental well-being in the past two weeks.	On day 1 and after 30 days

Collaborators and Investigators

• Sponsor: German Institute of Human Nutrition
• Investigators: Principal Investigator: Soyoung Q Park, Prof. Dr., German Institute of Human Nutrition Potsdam-Rehbruecke

Publications and helpful links

Helpful Links

• Abler, B. & Kessler, H. (2011). ERQ. Emotion Regulation Questionnaire [Verfahrensdokumentation aus PSYNDEX Tests-Nr. 9006192 und Fragebogen]. In Leibniz-Zentrum für Psychologische Information und Dokumentation (ZPID) (Hrsg.), Elektronisches Testarchi
• Scherhorn, G., Haas, H., Hellenthal, F., & Seibold, S. (1999). Kausalitätsorientierungen. Zusammenstellung sozialwissenschaftlicher Items und Skalen (ZIS).
• Forstmeier, S., & Maercker, A. (2011). Selbstkontrolle im höheren Erwachsenenalter: Eine deutsche Version des Delay Discounting Tests von Kirby. PPmP - Psychotherapie · Psychosomatik · Medizinische Psychologie, 61(06), e19-e33.
• Bornemann, B., Herbert, B. M., Mehling, W. E., & Singer, T. (2015). Differential changes in self-reported aspects of interoceptive awareness through 3 months of contempl tive training. Frontiers in Psychology, 5.
• Jerusalem, M., & Schwarzer, R. (2003). SWE - Skala zur Allgemeinen Selbstwirksamkeitserwartung. ZPID (Leibniz Institute for Psychology) - Open Test Archive.
• Grimm, Jürgen (Hg.) (2009): State-Trait-Anxiety Inventory nach Spielberger. Deutsche Lang- und Kurzversion. - Methodenforum der Universität Wien: MF-Working Paper 2009/02
• Lang, G., & Bachinger, A. (2017). Validation of the German Warwick-Edinburgh Mental Well-Being Scale (WEMWBS) in a community-based sample of adults in Austria: A bi-factor modelling approach. Journal of Public Health, 25(2), 135-146.
• Gueguen, M. C. M., Anlló, H., Bonagura, D., Kong, J., Hafezi, S., Palminteri, S., & Konova, A. B. (2024). Recent Opioid Use Impedes Range Adaptation in Reinforcement Learning in Human Addiction. Biological Psychiatry, 95(10), 974-984.
• Liu, L., Artigas, S. O., Ulrich, A., Tardu, J., Mohr, P. N. C., Wilms, B., Koletzko, B., Schmid, S. M., & Park, S. Q. (2021). Eating to dare- Nutrition impacts human risky decision and related brain function. NeuroImage, 233, 117951.

Study record dates

Study Major Dates

• Study Start (Actual): August 28, 2025
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): December 31, 2026

Study Registration Dates

• First Submitted: March 18, 2025
• First Submitted That Met QC Criteria: March 26, 2025
• First Posted (Actual): April 3, 2025

Study Record Updates

• Last Update Posted (Actual): April 21, 2026
• Last Update Submitted That Met QC Criteria: April 17, 2026
• Last Verified: September 1, 2025

More Information

Terms related to this study

• Keywords: Stress; Psychology; Decision-Making; Cold-Exposure; Cold-Water Immersion
• Additional Relevant MeSH Terms: Behavior
• Other Study ID Numbers: CoVa; 01GP2210C (Other Grant/Funding Number: German Federal Ministry of Education and Research)

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No