Inclusion Criteria:
* Healthy, men and women aged 18-39 years old. Active-duty military personnel who are 17 years of age will also be allowed to participate.
* Willing to refrain from the use of caffeine - including dietary supplements that contain caffeine - alcohol, and nicotine 24 hours prior to data collection.
* Willing to refrain from vigorous physical activity 24 hours prior to data collection.
* Willing to refrain from any dietary supplement use within one week of initial screening and at any time while enrolled in the study (except a multi-vitamin containing up to 100% RDA).
* Willing to consume study diets throughout the course of the study.
* Supervisory approval for participation if permanent party military or a federal employee.
Exclusion Criteria:
* Use of modafinil or armodafinil in the last 3 months.
* Known allergy to modafinil or armomodafinil.
* Current medical profile, or condition, that limits, compromises, or is likely to render inconsistent performance with Grip Strength, Finger Tapping, or cardiovascular exercise on an exercise bike.
* 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 CYP3A4 (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 steroids; 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.
* Females who are pregnant or breastfeeding, have a positive- pregnancy test, or plan on becoming pregnant in the next 3 months.
* Individuals currently taking/using contraceptives (i.e., oral contraceptive pill, intrauterine device, contraceptive implant, contraceptive injection, etc.) other than condoms.
* Current or history of mental health issues, illness, or condition (i.e., attention deficit hyperactivity disorder, autism spectrum disorder, diagnosed depression or anxiety disorders) that OMSO physician/healthcare provider believes puts the volunteers at increased risk.
* Current or history of psychosis, or history of suicidal or homicidal ideations within the past 2 years.
* History of cold injuries or cold-induced asthma.
* Raynaud's syndrome.
* Previous hand/finger injuries that impair dexterity and hand function.
* Metal hardware (plates/screws) in the upper extremities (arm/hands).
* Abnormal blood count (For example: hemoglobin (Hb) outside of the typical normal values reported by LabCorp in accordance with OMSO (Normal \[Hb\] Males = 12.6-17.7 g/dL; Females = 11.1-15.9 g/dL) or hematocrit (Hct) outside of the normal ranges (Normal Hct Males = 37.5-51.0%; Females = 34.0-46.6%) levels, presence of abnormal blood laboratory measures (e.g., hemoglobin S or sickle cell traits).
* Current or history of alcohol abuse (defined as Harmful Use by the World Health Organization), those who meet criteria for alcohol abuse disorder (as outlined in the DSM-5), or other substance abuse (i.e., the use of illegal drugs or the use of prescription or over-the-counter drugs for purposes other than those for which they are meant to be used, or in excessive amounts).
* Diagnosed sleep disorders (i.e., sleep-apnea, narcolepsy, etc.).
* Diseases and disorders of the metabolic, cardiovascular, endocrine, neurological, or gastrointestinal systems that in determination of OMSO are expected to interfere with safe conduct of the study.
* A medical diagnosis of high blood pressure (hypertension).
* Heart problems or prior heart attack.
* Regular daily use of medication that may significantly interfere with the study drug or outcomes, as determined by the OMSO physician/healthcare provider.
* Known allergies to medical adhesives.
* Difficulty swallowing large pills (self-reported) for those individuals unwilling to utilize the rectal suppository of the telemetric pill.
* History of obstructive disease of the gastrointestinal tract including (but not limited to) diverticulosis, diverticulitis and inflammatory bowel disease, peptic ulcer disease, Crohn's disease, ulcerative colitis, or previous gastrointestinal surgery, etc. that OMSO physician/healthcare provider believes puts the volunteers at increased risk.
* Donated blood within 8 weeks prior to study participation.
