Cold Water and Decision-Making

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.

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.

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)