This pilot study investigates the effects of cold-water immersion, traditional sauna use, and their combination on sleep architecture, glymphatic clearance, and psycho-affective health in military cadets. The study uses wearable technologies including the Oura Ring and the Applied Cognition Glymphatic Monitor to collect objective sleep and physiological data.
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, glymphatic function, and psycho-affective health will be assessed using validated wearable devices and questionnaires. The study aims to identify intervention-specific improvements in sleep and glymphatic clearance.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
45
Participants will complete 14 daily sessions of cold-water immersion exposure.
Participants will complete 14 evening sessions in the high heat sauna
The Citadel Military College
Charleston, South Carolina, United States
Glymphatic clearance
Changes in parenchymal resistance during sleep
Time frame: End of baseline monitoring phase (Day 7), end of intervention week 1 (Day 14), and end of intervention (Day 28)
Sleep Efficiency
Percentage of sleep period spent asleep measured by the Oura Ring (percentage, %)
Time frame: Each night of the baseline monitoring period (7days) and intervention phase (14days)
Pittsburgh Sleep Quality Index
Self-reported sleep quality
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)
Profile of Mood States: Total Mood Disturbance
Self-reported mood disturbance used by summing all negative profiled mood sub-scores (tension, depression, anger/hostility, fatigue, and confusion) and subtracting the positive profiled mood sub-score (vigor). (score -32 - 200, higher equals greater mood disturbance)
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)
Total Sleep Duration
Total duration of sleep period measured by the Oura Ring (seconds, s)
Time frame: Each night of the baseline monitoring period (7days) and intervention phase (14days)
REM Sleep Duration
Duration of sleep period spent in REM sleep measured by the Oura Ring (seconds, s)
Time frame: Each night of the baseline monitoring period (7days) and intervention phase (14days)
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Deep Sleep Duration
Duration of sleep periods spent in deep (N3) sleep (seconds, s)
Time frame: Each night of the baseline monitoring period (7days) and intervention phase (14days)
Light Sleep Duration
Duration of sleep period spent in light (N1 or N2) sleep (seconds, s)
Time frame: Each night of the baseline monitoring period (7days) and intervention phase (14days)
Restless Sleep Duration
Duration of sleep period with increased registered movements as measured by the Oura Ring (seconds, s)
Time frame: Each night of the baseline monitoring period (7days) and intervention phase (14days)
Wake After Sleep Onset (WASO) Duration
Total time spent awake after falling asleep (seconds, s)
Time frame: Each night of the baseline monitoring period (7days) and intervention phase (14days)
RMSSD
Root mean squared of temporal latency between successive heart beats throughout sleep period measured by the Oura Ring (milliseconds, ms)
Time frame: Each night of the baseline monitoring period (7days) and intervention phase (14days)
Nighttime Skin Temperature
Skin temperature (degrees Celsius, C°) throughout sleep period measured by the Oura Ring.
Time frame: Each night of the baseline monitoring period (7days) and intervention phase (14days)
Profile of Mood States: Tension/Anxiety
Tension/Anxiety sub-score computed from the POMS (score 0 - 36, higher equals more tension/anxiety)
Time frame: End of baseline monitoring period (Day 7), end of intervention week 1 (Day 14), and end of intervention (Day 28).
Profile of Mood States: Depression
Depression sub-score from the POMS (score 0 - 60, higher equals greater depression)
Time frame: End of baseline monitoring period (Day 7), end of intervention week 1 (Day 14), and end of intervention (Day 28)
Profile of Mood States: Anger/Hostility
Anger/Hostility sub-score from the POMS (score 0 - 48, higher equals greater anger/hostility)
Time frame: End of baseline monitoring period (Day 7), end of intervention week 1 (Day 14), and end of intervention (Day 28)
Profile of Mood States: Vigor
Vigor sub-score from the POMS (score 0 - 32, higher equals more vigor)
Time frame: End of baseline monitoring period (Day 7), end of intervention week 1 (Day 14), and end of intervention (Day 28)
Profile of Mood States: Fatigue
Fatigue sub-score from the POMS (score 0 - 28, higher equals more fatigue)
Time frame: End of baseline monitoring period (Day 7), end of intervention week 1 (Day 14), and end of intervention (Day 28)
Profile of Mood States: Confusion
Confusion sub-score from the POMS (score 0 - 28, higher equals more confusion)
Time frame: End of baseline monitoring period (Day 7), end of intervention week 1 (Day 14), and end of intervention (Day 28)
Sleep Time Heart Rate
Average heart rate during sleep (beats per minute, bpm)
Time frame: Each night of the baseline monitoring period (7days) and intervention phase (14days)