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NCT Number: NCT07201935

Thermodynamic Exposure and Sleep in Military Cadets

This pilot study investigates the effects of cold-water immersion, traditional sauna use, and their combination on sleep architecture and psychological health in military cadets. The study uses wearable technologies including the Oura Ring to collect objective sleep and physiological data.

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Key information

Conditions

Cold-water Immersion Combination of Cold-water Immersion and High Heat Sauna Dyssomnias High Heat Sauna Mental Disorders Nervous System Diseases Sleep Disorders, Intrinsic Sleep Initiation and Maintenance Disorders Sleep Wake Disorders

Age range

18 year–30 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

The Citadel Military College

Charleston, South Carolina, 29404, United States

Location contact

Geoffery Mcleod, DO

CONTACT

[email protected]

843-953-4827

About this study

The study will enroll 45 military cadets from The Citadel Military College, randomized into three groups: Cold-Water Immersion (CWI), High Heat Sauna (HHS), and Combined (COM). Participants will undergo a 7-day baseline period followed by a 14-day intervention. Sleep architecture and psychological-affective health will be assessed using validated wearable devices and questionnaires. The study aims to identify intervention-specific improvements in sleep and psychological health.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • 18 - 30 years of age 2. Enrolled military cadet at the Citadel Military College. 3. Access to a smartphone with access to appropriate app marketplace (Apple iOS 15, Android 8.0 or newer) and reliable data access.
  • Ability to access and operate Oura Ring application. Exclusion Criteria
  • Medical contraindications to continuous wearing of the Oura Ring.
  • Current diagnosis of neurological conditions that impact vascular blood flow or the individual's ability to regulate temperature.
  • History of cardio-vascular conditions or history of poor blood circulation.
  • History of heat stroke or known sensitivity to hot/cold environments.
  • Currently taking medications that impair fluid balance, thermoregulation, blood flow, respiration, or heart rate.
  • Known dermatological disease aggravated by changes in temperature.
  • Pregnant or trying to become pregnant within the study timeframe. Urine samples will be provided by interested female cadets to ensure they are not pregnant.

Treatment and study plan

Cold Water Immersion

Behavioral

Participants will complete 14 daily sessions of cold-water immersion exposure.

High Heat Sauna

Behavioral

Participants will complete 14 evening sessions in the high heat sauna

Primary outcomes

  1. Sleep Efficiency

    Time frame: Each night of the baseline monitoring period (7days) and intervention phase (14days)

    Percentage of sleep period spent asleep measured by the Oura Ring (percentage, %)

  2. Pittsburgh Sleep Quality Index

    Time frame: At the end of the baseline monitoring phase (Day 7), end of intervention week 1 (Day 14), and end of intervention phase (Day 28)

    Self-reported sleep quality

  3. Brief Mood Introspection Scale

    Time frame: At the end of the baseline monitoring phase (Day 7), end of intervention week 1 (Day 14), and end of intervention phase (Day 28)

    Self-reported assessment of mood consisting of 16 mood adjectives. Participants rate each adjective on a 4-point likert scale (0 = definitely don't feel, 3 = definitely feel). The assessment captures 2 core dimensions of mood valence (pleasant v. unpleasant) and arousal (active v. calm).

Secondary outcomes

  1. Total Sleep Duration

    Time frame: Each night of the baseline monitoring period (7days) and intervention phase (14days)

    Total duration of sleep period measured by the Oura Ring (seconds, s)

  2. REM Sleep Duration

    Time frame: Each night of the baseline monitoring period (7days) and intervention phase (14days)

    Duration of sleep period spent in REM sleep measured by the Oura Ring (seconds, s)

  3. Deep Sleep Duration

    Time frame: Each night of the baseline monitoring period (7days) and intervention phase (14days)

    Duration of sleep periods spent in deep (N3) sleep (seconds, s)

  4. Light Sleep Duration

    Time frame: Each night of the baseline monitoring period (7days) and intervention phase (14days)

    Duration of sleep period spent in light (N1 or N2) sleep (seconds, s)

  5. Restless Sleep Duration

    Time frame: Each night of the baseline monitoring period (7days) and intervention phase (14days)

    Duration of sleep period with increased registered movements as measured by the Oura Ring (seconds, s)

  6. Wake After Sleep Onset (WASO) Duration

    Time frame: Each night of the baseline monitoring period (7days) and intervention phase (14days)

    Total time spent awake after falling asleep (seconds, s)

  7. RMSSD

    Time frame: Each night of the baseline monitoring period (7days) and intervention phase (14days)

    Root mean squared of temporal latency between successive heart beats throughout sleep period measured by the Oura Ring (milliseconds, ms)

  8. Nighttime Skin Temperature

    Time frame: Each night of the baseline monitoring period (7days) and intervention phase (14days)

    Skin temperature (degrees Celsius, C°) throughout sleep period measured by the Oura Ring.

  9. Sleep Time Heart Rate

    Time frame: Each night of the baseline monitoring period (7days) and intervention phase (14days)

    Average heart rate during sleep (beats per minute, bpm)

Sponsors and collaborators

Lead sponsor

Medical University of South Carolina

Other

Registry information

Official study title

Hot, Cold, and Combined Thermodynamic Exposure to Improve Sleep Quality Among Military Cadets

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Oct 1, 2025
Registry last updated
May 19, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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