Soviet psychophysiological investigations of simulated isolation: some results and prospects

Human challenges to adaptation to extreme professional environments: A systematic review

NASA is planning human exploration of the Moon, while preparations are underway for human missions to Mars, and deeper into the solar system. These missions will expose space travelers to unusual conditions, which they will have to adapt to. Similar conditions are found in several analogous environments on Earth, and studies can provide an initial understanding of the challenges for human adaptation. Such environments can be marked by an extreme climate, danger, limited facilities and supplies, isolation from loved ones, or mandatory interaction with others. They are rarely encountered by most human beings, and mainly concern certain professions in limited missions. This systematic review focuses on professional extreme environments and captures data from papers published since 2005. Our findings provide an insight into their physiological, biological, cognitive, and behavioral impacts for better understand how humans adapt or not to them. This study provides a framework for studying adaptation, which is particularly important in light of upcoming longer space expeditions to more distant destinations.

Space missions: psychological and psychopathological issues

Exploring space is one of the most attractive goals that humanity ever set, notwithstanding, there are some psychological and psychopathological risks that should be considered. Several studies identified some possible hazards of space travels and related physical and psychological consequences on astronauts. If some psychological reactions are obviously inherent to the characteristics of the spaceships (habitability, confinement, psychological, and interpersonal relationships), other (disturbances of sleep-wake cycle, personality changes, depression, anxiety, apathy, psychosomatic symptoms, neurovestibular problems, alterations in cognitive function, and sensory perception) represent a clear warning of possible central nervous system (CNS) alterations, possibly due to microgravity and cosmic radiation. Such conditions and eventual CNS changes might compromise the success of missions and the ability to cope with unexpected events and may lead to individual and long-term impairments. Therefore, further studies are needed, perhaps, requiring the birth of a novel branch of psychology/psychiatry that should not only consider the risks related to space exploration, but the implementation of targeted strategies to prevent them.

Affective health and countermeasures in long-duration space exploration

Background

Space research is shifting attention toward interplanetary expeditions. Therefore, whether long-duration spaceflight may influence affective health is becoming an urgent issue.

Method

To this end, we undertook a literature search and reviewed several behavioral simulation studies on Earth that focused on affective components in space. We concluded with studies showing how spaceflight can impact on affective health of astronauts with a positively laden trajectory.

Results

By analyzing the multifaceted theoretical concept of affective health, we show that there is a variety of affective states (e.g., stress, coping, adaptation, and resilience) that can be differently affected by spaceflight.

Conclusions

Countermeasures geared toward promoting positive emotions could play a key role in positive adaptation to extreme environments and thus during long-duration space missions may benefit. Subjective resilience plays a mediating role in adaptation, but its definition needs to be deepened in order to develop robust countermeasures that may prevent the onset of emotional disorders.

Effects of 15-Day Head-Down Bed Rest on Emotional Time Perception

Accurate time perception is clearly essential for the successful implementation of space missions. To elucidate the effect of microgravity on time perception, we used three emotional picture stimuli: neutral, fear, and disgust, in combination with a temporal bisection task to measure 16 male participants’ time perception in 15 days of –6° head-down bed rest, which is a reliable simulation model for most physiological effects of spaceflight. We found that: (1) participants showed temporal overestimation of the fear stimuli in the middle phase (day 8), suggesting that when participants’ behavioral simulations were consistent with the action implications of the emotional stimuli, they could still elicit an overestimation of time even if the subjective arousal of the emotional stimuli was not high. (2) Participants’ temporal sensitivity tends to get worse in the bed rest phase (days 8 and 15) and better in the post-bed rest phase, especially for neutral and fear stimuli, suggesting that multiple presentations of short-term emotional stimuli may also lead to a lack of affective effects. This reduced the pacemaker rate and affected temporal perceptual sensitivity. Also, this may be related to changes in physiological factors in participants in the bed rest state, such as reduced vagal excitability. These results provide new evidence to support the theory of embodied cognition in the context of time perception in head-down bed rest and suggest important perspectives for future perception science research in special environments such as microgravity.

The Burden of Space Exploration on the Mental Health of Astronauts: A Narrative Review

Space travel, a topic of global interest, has always been a fascinating matter, as its potential appears to be infinite. The development of advanced technologies has made it possible to achieve objectives previously considered dreams and to widen more and more the limits that the human species can overcome. The dangers that astronauts may face are not minimal, and the impacts on physical and mental health may be significant. Specifically, symptoms of emotional dysregulation, cognitive dysfunction, disruption of sleep-wake rhythms, visual phenomena and significant changes in body weight, along with morphological brain changes, are some of the most frequently reported occurrences during space missions. Given the renewed interest and investment on space explorations, the aim of this paper was thus to summarize the evidence of the currently available literature, and to offer an overview of the factors that might impair the psychological well-being and mental health of astronauts. To achieve the goal of this paper, the authors accessed some of the main databases of scientific literature and collected evidence from articles that successfully fulfilled the purpose of this work. The results of this review demonstrated how the psychological and psychiatric problems occurring during space missions are manifold and related to a multiplicity of variables, thus requiring further attention from the scientific community as new challenges lie ahead, and prevention of mental health of space travelers should be carefully considered.

Acclimation during space flight: effects on human emotion

Recently, studies on the extent to which spaceflight affects the psychology of individuals has received attention. In order to reveal the mental challenges that humans face in space, we need practical viewpoints to integrate the psychological effects, behavior, performance and the environment itself for space exploration. The present review discusses the individual variables related to space psychology and manned spaceflight, in addition to their growing trends. These items include patterns of emotional changes in extreme environments and the approaches to evaluating emotions. Moreover, the review concludes with suggested future research on emotion during spaceflight and its analogs. These data and information are needed to plan for the exploration of the Moon and Mars, along with contributions to the construction of the international space station (ISS) and astronaut training.

Human missions to Mars: new psychological challenges and research issues

Human exploratory missions to Mars represent the most exciting future vision of human space flight. With respect to the distance to travel and mission duration, these missions will provide unique psychological challenges that do not compare to any other endeavor humans ever have attempted. The present paper presents outcomes of two recent projects sponsored by the European Space Agency--Humex and Reglisse--where these challenges and risks have been analyzed in some detail, and where concepts for future research have been developed. This presentation involves three steps. At first, it will be shown that our current psychological knowledge derived from orbital spaceflight and analogue environments is not sufficient to assess the specific risks of mission into outer space. Secondly, new psychological challenges of missions to Mars will be identified with respect to three different areas: (1) individual adaptation and performance, (2) crew interactions, and (3) concept and methods of psychological countermeasures. Finally, different options and issues of preparatory psychological research will be discussed.

Hormonal changes during long-term isolation

Confinement and inactivity induce considerable psychological and physiological modifications through social and sensory deprivation. The aim of the SFINCSS-99 experiment was to determine the cardiovascular and hormonal pattern of blood volume regulation during long-term isolation and confinement. Simulation experiments were performed in pressurized chambers similar in size to the volumes of modern space vehicles. Group I consisted of four Russian male volunteers, who spent 240 days in a 100-m(3 )chamber. Group II included four males (one German and three Russians) who spent 110 days in isolation (200-m(3) module). The blood samples, taken before, during and after the isolation period, were used to determine haematocrit (Ht), growth hormone (GH), active renin, aldosterone, and osmolality levels. From the urine samples, electrolytes, osmolality, nitrites, nitrates, cortisol, antidiuretic hormone (ADH), aldosterone, normetanephrine and metanephrine levels were determined. The increase in plasma volume (PV) that is associated with a tendency for a decrease in plasma active renin is likely to be due to decreased sympathetic activity, and concords with the changes in urinary catecholamine levels during confinement. Urinary catecholamine levels were significantly higher during the recovery period than during confinement. This suggests that the sympathoadrenal system was activated, and concords with the increase in heart rate. Vascular resistance is determined by not only the vasoconstrictor but also vasodilator systems. The ratio of nitrite/nitrate in urine, as an indicator of nitric oxide release, did not reveal any significant changes. Analysis of data suggests that the duration of the isolation was a main factor involved in the regulation of hormones.