Human Adaptations to Multiday Saturation on NASA NEEMO.

Area of Science:

• Human physiology
• Extreme environment adaptation
• Space-flight analog research

Background:

• Human adaptation to extreme environments is crucial for understanding physiology and psychology.
• Multiday hyperbaric and/or saturated (HBS) environments are understudied due to experimental challenges.
• The National Aeronautic Space Agency (NASA) Extreme Environment Mission Operation (NEEMO) provides a unique analog for space-flight research.

Purpose of the Study:

• To investigate human objective and subjective adaptations to multiday HBS.
• To evaluate aquanauts' psychologic, cardiac, respiratory, autonomic, thermic, hemodynamic, sleep, and body composition parameters.
• To gain insights into human adaptation across multiple body systems in HBS environments.

Main Methods:

• Aquanauts lived in saturation for 9-10 days during NASA NEEMO 22 and 23 missions.
• Evaluated psychologic, cardiac, respiratory, autonomic, thermic, hemodynamic, sleep, and body composition.
• Utilized the Aquarius Undersea Research Laboratory (AURL), an operational undersea saturated environment.

Main Results:

• Aquanauts experienced intrapersonal physical and mental burden but maintained positive mood and work satisfaction.
• Observed decreased heart and respiratory rates, increased parasympathetic and reduced sympathetic modulation.
• Noted lower cerebral blood flow velocity, intact cerebral autoregulation, and baroreflex functionality, alongside body weight and adipose tissue loss.

Conclusions:

• Multiday HBS exposure induces significant physiological and psychological adaptations.
• Human adaptation involves a balance between physical/mental burden and maintained psychological well-being.
• Findings offer novel insights into human resilience in extreme, isolated environments like undersea habitats and space.