The Effect of Water Temperature on Heart Rate Variability and Cognition

NCT07654270 | Not Yet Recruiting

• 1 other identifier: STUDY00024174
• Study Type: interventional
• Target: 30
• Locations: 0 countries
• Sites: N/A

Brief Summary

Heart rate variability (HRV) is a key indicator of fitness, and stress resilience. Previous research has shown that HRV decreases under mental workload, including during tasks that require strict attention. Studies also show that temperature exposure affects attention: cold increases the stress response while warm water has a calming effect. Very few studies combine thermal exposure with cognitive testing, and no controlled trials have investigated whether water temperature modulates HRV responses specifically during cognitive demand.

Conditions

Mental Acuity

Keywords

heart rate variability; water temperature; cognitive performance

Outcome Measures

Primary Outcomes (2)

• heart rate variability

  the measure of the variation in time between consecutive heartbeats

  3 minutes

• cognitive performance

  Trail making test that measures cognitive flexibility, visual attention, and executive function, with interpretation based on completion times (in seconds)

  3 minutes

Secondary Outcomes (2)

• cognitive performance

  3 minutes

• cognitive performance

  3 minutes

Study Arms (2)

Warm water

EXPERIMENTAL

Water will be heated to \~55º C (131 ºF)

Other: water

Cold water

PLACEBO COMPARATOR

Cold water: 4-6º C (41ºF)

Other: water

Interventions

water OTHER

water temperature

Cold water; Warm water

Eligibility Criteria

• Age: 18 Years - 30 Years
• Gender Eligibility Details: female
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Healthy women free of chronic disease (by self-report)
• years of age

You may not qualify if:

• medication/drug use that has not been consistent for the previous 3 months or will be discontinued during the trial
• any acute illness
• regular use of cigarettes or marijuana
• pregnant or lactating women
• not fluent in English
• not willing to attend two in-person lab visits in downtown Phoenix and follow study protocol (including abstaining from caffeine in the 12 hours prior to testing)
• not currently competing in sports or unusually high-intensity exercise protocols (e.g., high-intensity exercise greater than 30 minutes most days of the week)

Sponsors & Collaborators

• Arizona State University: lead

MeSH Terms

Interventions

Water

Intervention Hierarchy (Ancestors)

Hydroxides; Alkalies; Inorganic Chemicals; Anions; Ions; Electrolytes; Oxides; Oxygen Compounds

Study Officials

• Carol Johnston

  Arizona State University

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Carol Johnston

CONTACT

6024963463; carol.johnston@asu.edu

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Masking Details: Masking water temperature is not possible.
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor and Senior Associate Dean

Model Details: This is a crossover study and all participants will receive both treatments one week apart in randomized order.

Study Record Dates

• First Submitted: June 10, 2026
• First Posted: June 17, 2026
• Study Start (Estimated): July 13, 2026
• Primary Completion (Estimated): December 15, 2026
• Study Completion (Estimated): June 15, 2027
• Last Updated: June 17, 2026

Record last verified: 2026-06

Data Sharing

• IPD Sharing: Will not share