Neurobehavioral Changes Following Spaceflight Stressors

This study aims to investigate the impairing effects of known central nervous system (CNS) stressors in a controlled environment in order to predict and mitigate analogous risks in spaceflight. Up to 56 healthy individuals aged 25-60 will spend six days and five nights (24 hours a day) in a laboratory, where they will be exposed to 27 hours of sleep deprivation and will consume alcohol to reach a BAC of 0.08 on a separate day. They will also have an adaptation night, a control condition with no daytime or nighttime interventions, and a recovery night following the sleep deprivation condition. All subjects in a group will receive the three conditions (sleep deprivation, alcohol administration and control) in the same order, but this order will vary between study runs.

Subjects will perform cognitive tests and sensorimotor tasks throughout the waking periods. They will undergo one MRI and two blood draws for each of the three conditions, for a total of three MRIs and six blood draws per subject. The scans and blood draws are timed to occur near the highest predicted level of impairment in order to capture the dose-response relationship between the stressor and performance. Combined with research from parallel rodent studies performed at a partner institution where rodents are exposed to alcohol administration, sleep deprivation and radiation, these data may allow us to estimate the performance decrements associated with exposure to radiation in humans to assess the radiation risks of spaceflight.

Inclusion criteria

• Age between 25-60 years.
• Free of psychological, psychiatric or physical conditions that preclude participation.
• BMI between 18.5 and 35.
• Self-reported regular sleep schedule; able to maintain their sleep schedule during the course of the study.
• Self-reported sleep duration of 6-8.5 h per night (verified by daily logs).
• Ability to read/write English.
• Able to stand unassisted for up to 10 minutes at a time and able to lift arms above head.

Exclusion criteria

• Alcohol or drug abuse in the past year based upon history and urine toxicology screen.
• Potential alcohol abuse or heavy drinking in the past year, based on self-report (AUDIT-C Q2 score above 1 or Q3 score above 2).
• Alcohol-naive based on self-report (AUDIT-C Q1 score of 0).
• Allergies, conditions or circumstances that preclude alcohol consumption, including use of medication or supplements (prescription or over the counter) that could interfere with study participation or make it hazardous for a subject to partake (e.g., anticholinergics; antipsychotics; lithium; psychotropic drugs not otherwise specified), or for which alcohol consumption should be limited or avoided (e.g. items identified on NIAAA's 'Harmful Interactions' list).
• Cultural or personal beliefs that preclude alcohol consumption.
• Body Mass Index ≤18.5 or ≥ 35.
• Current smoker/tobacco user or using nicotine replacement therapy. Those that have been nicotine-free for ≥ 30 days may be included.
• Excessive caffeine consumption (> 650mg/day combining all caffeinated drinks regularly consumed during the day).
• Acute, chronic, or debilitating medical conditions, major Axis I psychiatric illness based on history, physical exam, blood and urine chemistries; or self-reported history of neurological, psychiatric, or other medical condition that precludes participation, such as nervous system disorders, dementia, chronic migraines, or epilepsy; panic, bipolar or schizoaffective disorder; sleep disorders including insomnia, narcolepsy and obstructive sleep apnea; liver, kidney or heart disease, hypertension; infectious diseases; diabetes; or any other conditions for which medical monitoring is advised and which may require medications and/or lifestyles that preclude alcohol consumption and/or sleep disruption.
• Current depression as determined on the Beck Depression Inventory (Beck, 1996), by either a total score of 19 or higher or a response greater than 0 on Q9 (suicidality).
• Cardiovascular, gastrointestinal, or musculoskeletal problems, or other major conditions such as organ failure, cancer or patients requiring oxygen.
• Prior history or diagnosis of any sleep disorder including Obstructive Sleep Apnea (AHI ≥15 events/hour) - from ambulatory or in lab polysomnography; Restless legs syndrome or periodic limb movement disorder; Insomnia; Parasomnia; High Risk of OSA based on STOP-BANG Questionnaire ("yes" on at least 4 of 8 questions); High Risk of Restless Legs Syndrome (RLS) based on Cambridge-Hopkins Screening questionnaire; High Risk of Insomnia based on Insomnia Severity Index (score of 22 or higher).
• Current use or use within the past month of a prescription or over-the-counter sleep medication or stimulant (based on self-report or review with a study clinician).
• History of potential MRI contraindications, including: tinnitus; sensorineural hearing loss > 30 dB; pace maker or internal defibrillator; metallic implants (e.g. orthopedic plates after bone fractures, joint replacements, surgical staples or clips, artificial heart valves, stents, cava filters); metallic splinters (e.g. after an accident or due to war injury); non-removable dental brace; Tattoo (some tattoo inks contain metallic particles); permanent make-up; non-MRI compatible intrauterine contraceptive device; cochlear implant (implanted hearing device); medication pump; acupuncture needle; other foreign bodies/objects which are non-removable; pregnancy (or its possibility); previous brain and/or heart surgery.
• History of severe motion sickness, based on self-report or driving simulator response.
• Pregnant or currently breast feeding. People that menstruate will have a pregnancy test performed via urine sample during screening, as those that are currently pregnant are unable to participate in the study.
• Individuals who self-report severe contact dermatitis or allergy to bandages, silicone, nickel or silver.
• Currently working night, swing, split or rotating shift.
• Planned travel across more than one time zone within 7 days of the scheduled study start date.
• Habitual daytime napping.