Lost at sea: Impact of an ocean survival experience on psychological, physiological and cognitive abilities (RAD'LÔ)

Survival in an extreme environment places high physiological and cognitive demands on the individual. These environments are characterized by specific stimuli, including unusual sensory stimulation and uncertainty, which induce intense stress. Thus, the aims of this study are: i ) to evaluate the impact of a five-day survival at sea simulation on human adaptive capacities, based on the assessment of psychological, cognitive, physiological, and sensorial measures; and ii ) to assess recovery. Twenty-one healthy participants were enrolled in a 5-day simulation onboard a lifeboat or an inflatable raft. Psychological, physiological, sensory, and cognitive measurements were recorded before leaving (baseline), at the end of the experiment (post) and during the week that followed (recovery). Our results are unequivocal. The harshness of the environment affected the majority of the organism's responses. On the cognitive level, performance significantly deteriorated. On the psychological level, there was low mood, a decrease in subjective exteroceptive acuity and sleep disorders, increased energy, and less perceived stress. On the physiological level, a decline was recorded with respect to autonomous nervous system measurements. On the sensory level, we observed a state of hypervigilance and hypersensitivity to stimuli from the external environment. Proprioception was deeply impacted. Moreover, at recovery, many individuals did not fully recover or deteriorated further, especially regarding sleep, interoceptive abilities and sensory distortion. It appears that participants entered a state of psychological hibernation, associated with increased physical and cognitive load, and sensory hypervigilance. These results raise the question of the risks that may be incurred during future long-term space missions, as astronauts will have to maintain their cognitive performance at a high level to be able to respond to environmental demands and remain alive. It is essential to continue to explore countermeasures that will support adaptation in future spacecraft crew.