Modafinil to Optimize the Performance of Cold-Stressed Sleep-Deprived Personnel

DRUG

Modafinil (M)

Evaluating the effect of Modafinil under both sleep deprivation and acute cold exposure on thermoregulation, cognitive flexibility/performance, and dexterity.

DRUG

200 mg Microcrystalline Cellulose

Placebo intervention to compare to modafinil intervention.

Height (in)

Time frame: Familiarization 1 (Day -2)

Height will be measured in inches using a stadiometer.

Body Weight (kg)

Time frame: Familiarization 1 (Day -2)

Body weight will be measured in kilograms using a calibrated electronic scale.

Body Composition: DXA Fat Mass (lbs)

Time frame: Familiarization 1 (Day -2)

Fat mass will be measured in kilograms via dual x-ray absorptiometry and used to calculate body fat percentage (fat mass/body weight).

Body Composition: DXA Lean Mass (lbs)

Time frame: Familiarization 1 (Day -2)

Lean mass will be measured in pounds using dual x-ray absorptiometry.

Body Composition: DXA Bone Mineral Content (lbs)

Time frame: Familiarization 1 (Day -2)

Bone mineral content (BMC) will be measured in pounds using dual x-ray absorptiometry.

Sleep & Physical Activity

Time frame: Familiarization 1 to Study Completion (11 Days)

Physical activity and sleep duration will be recorded in minutes per day with a wrist actigraphy monitoring system (Actiwatch Spectrum Plus, Koninklijke Philips N.V., Amsterdam, NL or equivalent device). The accelerometer will be placed on the volunteer's wrist on the first familiarization day, worn continuously throughout the entirety of study participation (11 days total), and returned after a 2-day washout period after the second overnight collection. Activity and sleep measurements recorded by the accelerometer will be utilized to determine sleep/wake times of volunteers throughout the study duration.

Cold Exposure: Core Temperature

Time frame: Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)

Core temperature will be measured continuously at baseline (room temperature) and during cold exposure using a telemetric thermometer capsule (e-Celsius® Performance Capsule, BodyCap, Saint-Clair, France, or similar). Volunteers will either insert the capsule as a rectal suppository the morning of testing, or opt to ingest orally the night (at least 12 hours) prior to data collection to ensure deep core body temperature is accurately monitored. Volunteers will be removed from testing if core temperature decreases to 35 degrees Celcius or lower.

Cold Exposure: Skin Temperature

Time frame: Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)

Skin temperature will be continuously measured in Celcius at baseline (room temperature) and during cold exposure using Thermochron iButtons attached at the volunteer's chest, triceps, hand, thigh, calf, and foot.

Dexterity: Finger Tapping Task (FTT)

Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)

The FTT is an approximately 10 minute test used to assess manual dexterity and visuomotor coordination. Volunteers are asked to follow simply motor commands using their hands and fingers while seated using a standard 8-finger QWERTY keyboard position (left fingers resting on ASDF, right fingers resting on JKL;). Volunteers are presented varying finger tap sequences on a computer displaying spatially compatible keys matching the standard position (ASDFJKL;) and asked to press the corresponding key while wearing Army issued contact gloves. The presentation time of cues will be adjusted throughout the task at variable difficulties to assess visuomotor response thresholds. Volunteers are scored based on how quickly finger taps are correctly executed in the presented sequence without errors of omission, commission, or excursions.

Cognitive Assessment: Scanning Visual Vigilance

Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)

Volunteers will continuously scan a computer screen to detect stimuli that are present in irregular intervals approximately every 1 minute. Volunteers will be scored based on whether a stimulus is correctly detected (max score of 30), falsely detected, and the response time in milliseconds when detected. This task is sensitive to low doses of stimulants, nutritional factors, environmental conditions, and sleep loss.

Cognitive Assessment: Psychomotor Vigilance Test (PVT)

Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)

PVT is a 10-minute test of simple visual reaction time used to assess alertness. Volunteers will be scored based on reaction time, correct responses, and lapses (failure to detect stimuli).

Cognitive Assessment: Matching to Sample

Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)

Matching to Sample assesses short-term spatial memory (working memory) and pattern recognition. Volunteers are presented with a series of 8x8 matrices. Each matrix is displayed for 4 seconds, volunteers see a blank screen for 8 to 16 seconds, and then 2 matrices will be presented: one matrix identical to the original, and another slightly different to the original. Volunteers have 15 seconds to select the correct comparison matrix. Volunteers will be scored by correct responses, reaction time, and time-out errors.

Cognitive Assessment: Grammatical Reasoning

Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)

Grammatical reasoning assesses language-based logical reasoning. Volunteers will be presented with either the letters "AB" or "BA" followed by a statement that describes the order of the two letters (e.g. "A precedes B"). The volunteer must select whether the statement is true or false. Volunteers are scored based on accuracy and reaction time, with a max score of 32 correct responses.

Cognitive Assessment: Go/No-Go Task

Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)

The Go/No-Go Task is a 10 minute test that assesses response inhibition. Volunteers will randomly be presented with with a "+" or "x" on their screen during moderate exercise on a stationary bike. Volunteers will be instructed to press a button as quickly as possible in response to one visual stimulus, and withhold a response to the other visual stimulus. Number of correct responses, incorrect responses, and reaction time will be scored.

Cognitive Assessment: N-Back Task

Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)

The N-Bask Task is a 10 minute assessment of working memory. Volunteers will be shown a series of letters on a screen while performing moderate exercise on a stationary bike and asked to mentally take note of the letters shown. Volunteers will then be asked to respond "yes" or "no" by pressing the respective button if the letters currently displayed are the same letters that were displayed either 1, 2, and/or 3 letters back. Correct and incorrect responses will be recorded as a volunteer score.

Cognitive Assessment: Task-Switching Task

Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)

Task-Switching is a 10 minute assessment of cognitive flexibility. Volunteers will switch back and forth randomly between determining if the number presented on the screen is odd or even or if the number presented is above or below 5 while performing moderate exercise on a stationary bike. Volunteers will decipher which task is being performed based on the color of the number presented (pink or blue), and press the corresponding button on their keypad (odd/even or greater than/less than). Volunteers will be scored based on number of correct responses.

Physical Performance: Grip Strength

Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)

Grip strength will be measured in both hands to evaluate manual performance under cold stress using a hand dynamometer. Volunteers were asked to hold the dynamometer in a neutral position (shoulder adducted, elbow flexed to 90 degrees, forearm and wrist neutral) and instructed to squeeze the handle as hard as possible while maintaining a neutral position. Three repetitions will be completed for each hand, alternating hands between each trial. Grip strength for each hand was scored as the mean of the 3 trials, recorded in kilograms.

What is a clinical trial?

A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.

Is it safe to participate?

Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.

Will I be compensated?

Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.

Will I receive a placebo instead of treatment?

When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.

Can I leave a trial if I change my mind?

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How long does a clinical trial last?

Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.