A Phase 4 interventional study of Modafinil (M) and 200 mg Microcrystalline Cellulose in Sleep Deprivation and Cold Exposure, sponsored by United States Army Research Institute of Environmental Medicine. Completed at 1 site in United States. Open to participants aged 17 Years to 39 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-11-10.
Sponsored by United States Army Research Institute of Environmental Medicine · Phase 4, Interventional, and Treatment
Among 146 studies in Sleep Deprivation with a site in United States — 30 open to participants now, 35 under way, none of them phase 3. Sleep Deprivation · United States.
Among the 146 studies in Sleep Deprivation with a site in United States, this one is the 79th largest by enrollment of the 127 interventional ones, is one of 5 that started in 2025, is one of 7 in phase 4, and was the 143rd registered.
314 studies on the registry are indexed under Sleep Deprivation; 59 are open to participants now.
This study's enrollment of 33 is below the median of 50 across 259 interventional studies indexed under Sleep Deprivation.
Browse Sleep Deprivation studies →30 of the 146 studies in Sleep Deprivation with a site in United States are open now, in 2 countries. Each count lists the studies.
Of the 43 Sleep Deprivation studies recruiting now, 11 (26%) set no upper age limit and 28 (65%) stop at 75 or younger; 5 take children under 18; 29 take healthy volunteers.
This study: 17 Years to 39 Years · all sexes · healthy volunteers too.
The full table on the hub →146 studies; the count open now beside each. This study's row is marked.
First in 1999; this study’s year is marked. 5 started in 2025.
Median enrollment 56 across the 127 interventional studies, 64 across the 19 observational. Of the 106 that completed or were terminated, 27 (25%) have results posted.
13 of 146 have an industry lead sponsor. The 10 most frequent:
United States Army Research Institute of Environmental Medicine is the lead sponsor of 68 studies on the registry; 7 are open to participants now.
Of its 6 completed or terminated interventional studies of FDA-regulated products, 2 (33%) have results posted.
United States Army Research Institute of Environmental Medicine has 4 studies filed under Sleep Deprivation — fewer than ten, so there is no comparison to draw.
7 of the studies in Sleep Deprivation with a site in United States that are under way reach primary completion within a year, 0 of them phase 3. Phase 3 first, then by date:
| Study | Primary completion |
|---|---|
| NCT06642246Children's Hospital of PhiladelphiaSleep Promotion and Pediatric Hypertension | 2026-11 |
| NCT06336525Brigham and Women's HospitalAdult Sleep Health in the Rural Appalachia and Mississippi Delta Region and Its Relationships With Cardiometabolic Health Disparities. | 2027-01-31 |
| NCT05393830Beth Israel Deaconess Medical CenterThe Effect of Sleep Loss on Emotion Regulation | 2027-04-01 |
| NCT05703347Children's Hospital of PhiladelphiaOptimizing a Mobile Health Platform for Sleep Promotion and Obesity Prevention in Children | 2027-06 |
| NCT02945501U.S. Army Medical Research and Development CommandTranscranial Electrical Stimulation (TES) at Slow Oscillation (SO) Frequency During NREM Sleep | 2027-06 |
Among the 146 studies in Sleep Deprivation with a site in United States, from their registry updates:
Environmental and workplace stressors are common and often unavoidable in military operations. Two critical stressors are cold stress and sleep loss. They both can substantially degrade operational effectiveness. Various countermeasures are available to mitigate the adverse effects of these stressors, but due to operational requirements many are of limited use in the field. Modafinil is a drug that mitigates the effects of sleep deprivation and potentially cold stress, and modafinil may prevent performance degradation due to the combination of these stressors. This study will help determine if modafinil alters body-heat production and prevents cognitive and physical performance degradation due to cold stress in rested and sleep-deprived volunteers.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
a. Individuals taking substances that directly interact with modafinil, alertness/attention/concentration, or sympathetic tone: stimulants; decongestants, barbiturates, bronchodilators; SNRIs; opioids; appetite suppressants; anti-obesity medications; b. Individuals taking substances which inhibit (penicillins; macrolide antibiotics; fluoroquinolones; lomitapide; goldenseal) or MAO inhibitors.
c. Individuals taking substances which induce CYP3A4 (carbamazepine, phenobarbital, rifampin) to a greater than minimal degree: systemic ; anti-gout agents (Exceptions can be recommended to PI for CYP3A4 inducers which do not fall into other listed categories).
d. Individuals taking substances which are metabolized by CYP450 enzymes 1A2, 2B6, 2C19, or 3A4: immune-suppressant/-modulatory drugs; SSRIs; TCAs; anti-coagulants; antituberculosis agents; antimalarials; antineoplastic agents; antibody-derived drugs; antivirals; azole antifungals; anti-parasitic agents; abortive migraine medications; muscle relaxants; sex hormones or modulators; ibrexafungerp; lefamulin; palovarotene; propranolol.
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.
Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
The American Psychiatric Association’s manual of mental health diagnoses. DSM-5 (2013, revised as DSM-5-TR in 2022) replaced DSM-IV, and some studies still name the older edition. “Meets DSM criteria for …” means diagnosed by that edition’s diagnostic criteria, usually by a clinician in an interview.
CYP3A (CYP3A4) inhibitors and inducers
CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.
Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hemoglobin (Hb)
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
DSM diagnostic criteria
The American Psychiatric Association’s manual of mental health diagnoses. DSM-5 (2013, revised as DSM-5-TR in 2022) replaced DSM-IV, and some studies still name the older edition. “Meets DSM criteria for …” means diagnosed by that edition’s diagnostic criteria, usually by a clinician in an interview.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
200 mg Microcrystalline Cellulose
Drug: 200 mg Microcrystalline Cellulose
200 mg Modafinil
Drug: Modafinil (M)
Evaluating the effect of Modafinil under both sleep deprivation and acute cold exposure on thermoregulation, cognitive flexibility/performance, and dexterity.
Placebo intervention to compare to modafinil intervention.
Height (in)
Height will be measured in inches using a stadiometer.
Time frame: Familiarization 1 (Day -2)
Body Weight (kg)
Body weight will be measured in kilograms using a calibrated electronic scale.
Time frame: Familiarization 1 (Day -2)
Body Composition: DXA Fat Mass (lbs)
Fat mass will be measured in kilograms via dual x-ray absorptiometry and used to calculate body fat percentage (fat mass/body weight).
Time frame: Familiarization 1 (Day -2)
Body Composition: DXA Lean Mass (lbs)
Lean mass will be measured in pounds using dual x-ray absorptiometry.
Time frame: Familiarization 1 (Day -2)
Body Composition: DXA Bone Mineral Content (lbs)
Bone mineral content (BMC) will be measured in pounds using dual x-ray absorptiometry.
Time frame: Familiarization 1 (Day -2)
Sleep & Physical Activity
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.
Time frame: Familiarization 1 to Study Completion (11 Days)
Cold Exposure: Core Temperature
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.
Time frame: Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)
Cold Exposure: Skin Temperature
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.
Time frame: Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)
Dexterity: Finger Tapping Task (FTT)
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.
Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)
Cognitive Assessment: Scanning Visual Vigilance
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.
Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)
Cognitive Assessment: Psychomotor Vigilance Test (PVT)
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).
Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)
Cognitive Assessment: Matching to Sample
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.
Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)
Cognitive Assessment: Grammatical Reasoning
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.
Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)
Cognitive Assessment: Go/No-Go Task
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.
Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)
Cognitive Assessment: N-Back Task
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.
Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)
Cognitive Assessment: Task-Switching Task
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.
Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)
Physical Performance: Grip Strength
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.
Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)
Cognitive Assessment: Balloon Analogue Risk Task (BART)
The BART is used to assess risk-taking behavior, reportedly altered by sleep loss. Volunteers will repeatedly fill simulated balloons with air, and points are awarded each time the balloon inflates with air without "popping it". The more the balloon is inflated, the more points are earned. Volunteers can bank their points at any time. All points accumulated that are not banked will be lost if the balloon pops. Simulated balloons will randomly pop after either 8, 32, or 128 puffs. Volunteers will be scored based on how many balloons are popped in each of these categories.
Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)
Assessment of Blinding
Volunteers will complete a single item exit survey at the end of the second experimental visit to assess the potential of the placebo effect on cognitive and physical performance during cold exposures. Volunteers will be asked to report which experimental session they believe they consumed Modafinil, answering either: session 1, session 2, or not sure.
Time frame: Cold Exposure (Day 7)
Dietary Intake
Volunteers will be prescribed a standardized diet (1.2 g/kg protein, 6 g/kg carbohydrate, 1 g/kg fat) to moderate the potential influence of diet on performance during the experimental visits. Diet prescription will be based on volunteer body mass measured at the first familiarization visit. Volunteers will start diet prescription 48 hours prior to the first experimental visit at baseline assessment, and continue study diet through completion of second experimental visit (8 days total). Study dieticians will prepare individual diets derived from military combat rations (MRE; Meal, Ready-to-Eat) and commercially available food items. Dietary intake will be verified by collecting wrappers/containers and any food or drink that is not entirely consumed will be weighed and accounted for.
Time frame: Baseline Assessment (Day 0) to Cold Exposure (Day 7)
Cold Exposure: Environmental Symptoms Questionnaire (ESQ)
The ESQ was used to determine the effects of exposure to environmental extremes. A modified version of the ESQ was used to assess the effects relevant to cold exposure only. Volunteers were asked to rate statements on a scale from 1 (not at all) to 5 (extreme). Higher scores indicate that the volunteer is experiencing more severe symptoms of cold exposure.
Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)
Mood Assessment: Profile of Mood States Questionnaire (POMS 2-A)
The POMS is a 65-item inventory of mood states that asks volunteers to rate each mood-related adjective on a 5-point scale (0-4) based on how the volunteer is currently feeling. Mood states will be measured on 7 sub-scales: 1) tension/anxiety \[TA\], 2) depression/dejection \[DD\], 3) anger/hostility \[AH\], 4) vigor/activity \[VA\], 5) fatigue/inertia \[FI\], 6) confusion/bewilderment \[CB\], and 7) friendliness. Subscales 1-6 have a potential score of 0-44, while the friendliness subscale has a potential score of 0-40. Total mood disturbance is calculated as: \[(TA + DD + AH + FI + CB) - VA\] with a potential score of 0-176 . Higher scores indicate that the individual experiences more intense or more frequent negative mood states compared to the general population.
Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)
Mood Assessment: Buss-Perry Aggression Questionnaire
The Buss-Perry Aggression Questionnaire is a 29-item questionnaire that assesses aggressive impulses and thought patterns. Volunteers rank statements on a 5-point scale from "extremely uncharacteristic of me (1)" to "extremely characteristic of me (5)." Aggression is scored on 4 scales: 1) physical aggression, 2) verbal aggression, 3) anger, and 4) hostility. Volunteers are scored for each subscale: physical (scored 9-45), verbal (scored 5-25), anger (scored 7-35), and hostility (scored 8-40), as well as a total score of all items (scored 29-145). Higher scores indicate greater overall aggression.
Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)
Mood Assessment: Felt Arousal Scale (FAS)
The FAS is a one-item inventory measuring feelings of arousal ranging from 1 (low arousal) to 6 (high arousal). Volunteers will be asked to rate their current level of arousal in the final minute of the 15-minute bout of moderate exercise on a stationary bike. Higher scores indicate higher levels of arousal.
Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)
Mood Assessment: Feeling Scale (FS)
The FS is a one-item inventory measuring the extent to which pleasant or unpleasant feelings are currently experiencing. The FS ranges from 5 (very good) to -5 (very bad). Volunteers will complete the FS in the final minute of the 15 minute bout of moderate exercise on a stationary bike. Higher scores indicate the volunteer is experiencing more pleasant feelings while lower scores indicate the volunteer is experiencing more unpleasant feelings.
Time frame: Familiarization 1 (Day -2), Familiarization 2 (Day -1), Baseline Assessment (Day 0), Cold Exposure (Days 2 & 3), Cold Exposure (Days 6 & 7)
Resilience: Connor-Davidson Resilience Scale (CD-RISC-25)
The CD-RISC-25 was administered at the start of the first familiarization day to assess volunteer resilience as a potential moderating psychological factor. Volunteers were asked to rate 25 items on a scale from "not true at all" (0) to "true nearly all the time" (4). Scores can range from 0-100, with higher scores reflecting greater resilience.
Time frame: Familiarization 1 (Day -2)
Background Survey
A background survey will be administered at the start of the first familiarization day. Volunteers will be asked to report basic demographic information, tobacco and supplement use, military service, recent physical activity habits, and previous experience with cold exposure as potential moderating variables of cognitive and physical performance during experimental visits.
Time frame: Familiarization 1 (Day -2)
Adverse Events
Participants were asked to report any adverse events they may have experienced in the 24 hours following completion of 26-hour overnight cold exposures. Study staff met with volunteers to complete an in-person assessment the morning after overnight collection (Days 4 and 8) and provided a list of expected adverse events associated with Modafinil and sleep deprivation, as well as asked to report any other events/symptoms. Volunteers were asked to report whether they had experienced: trouble sleeping, nausea/other GI issues, headache, numbness or pain in fingers, numbness or pain in toes, other (specify), or no adverse event.
Time frame: Post Overnight Chamber Exposures (Days 5 & 8)
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: No
Ran from Feb 2025 to primary completion in Sep 2026, 19 months.
Since we started tracking on Sep 25, 2026, the dates moved once, on Nov 10, 2026: primary completion Oct 2026 → Sep 2026 and completion Dec 2026 → Sep 2026.
Earlier changes are on the record history on ClinicalTrials.gov ↗
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is completed, as verified in Nov 2026. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Modafinil
United States Army Research Institute of Environmental Medicine