Sleep in Isolated, Confined, and Extreme (ICE): A Review on the Different Factors Affecting Human Sleep in ICE

Space Analogs and Behavioral Health Performance Research review and recommendations checklist from ESA Topical Team

Space analog research has increased over the last few years with new analogs appearing every year. Research in this field is very important for future real mission planning, selection and training of astronauts. Analog environments offer specific characteristics that resemble to some extent the environment of a real space mission. These analog environments are especially interesting from the psychological point of view since they allow the investigation of mental and social variables in very similar conditions to those occurring during real space missions. Analog missions also represent an opportunity to test operational work and obtain information on which combination of processes and team dynamics are most optimal for completing specific aspects of the mission. A group of experts from a European Space Agency (ESA) funded topical team reviews the current situation of topic, potentialities, gaps, and recommendations for appropriate research. This review covers the different domains in space analog research including classification, main areas of behavioral health performance research in these environments and operational aspects. We also include at the end, a section with a list or tool of recommendations in the form of a checklist for the scientific community interested in doing research in this field. This checklist can be useful to maintain optimal standards of methodological and scientific quality, in addition to identifying topics and areas of special interest.

Effects of positive psychological control intervention on sleep and psychology of officers and soldiers working at sea

BACKGROUND

The working environment of submarine crews is also very special. They are in a closed, high-temperature, high-noise, high-vibration and narrow working and living space for a long time, and they suffer from physical discomfort caused by seasickness, which will affect the mental health of officers and soldiers. American psychologists have achieved positive results in psychological resilience training for officers and soldiers from the perspective of positive psychology. At present, there are few reports on the correlation between psychological resilience in the field of domestic research on submarine crew psychology, and it is necessary to conduct further research.

AIM

To explore the impact of active psychological regulation intervention on officers and soldiers operating in confined spaces at sea.

METHODS

A total of 121 soldiers working in a confined space of a large ship were randomly divided into an experimental group and a control group. The 50 soldiers in the experimental group were given a training course intervention, while the 71 soldiers in the control group did not receive any intervention measures. The Pittsburgh Sleep Quality Index, Psychological Resilience Scale, military Psychological Stress Self-Assessment Questionnaire, and General Self-Efficacy Scale scores were compared before and 6 months after the intervention.

RESULTS

Under the positive psychological control intervention, except for sleep efficiency (P = 0.05), the difference between the remaining dimensions of the Pittsburgh Sleep Quality Index scores and the total scores of the experimental group compared with the control group was statistically significant (P < 0.05); the assessment of the psychological condition showed that, in addition to the Psychological Stress Self-assessment Questionnaire for Military Personnel scores (P = 0.05), the scores of the Mental Toughness Scale (Dispositional Resilience Scale Resilience II) in the experimental group, General Self-Efficacy Scale scores were statistically significant (P < 0.05) compared to pre-intervention.

CONCLUSION

Positive psychological intervention and control can improve the sleep state and psychological state of officers and soldiers working in confined space at sea.

[Effects of Extreme Environments on Human Sleep]

Recently, with the rapid growth of the global population and the exhaustion of resources, exploration activities in extreme environments such as the polar regions, the outer space, the deep sea, the deep underground and highlands are becoming increasingly more frequent. This in-depth exploration of the external environment and the consequent dramatic changes in lifestyles impact on sleep, a basic life activity of humans, in ways that cannot be overlooked. the basic life activity of human beings. Sleep, a basic life activity and the result of the evolution of organisms to adapt to their environment, is closely associated with sleep homeostasis and endogenous rhythms. However, external environmental changes and lifestyle shifts in extreme environments have had a significant impact on the patterns and the quality of sleep in humans. Furthermore, this impact can lead to many physiological and psychological problems, posing a great threat to human health. In this review, we delved into the specific effects of different extreme natural environments and enclosed environments on sleep, elaborating on how these environments alter the patterns and the quality of sleep in humans. In addition, we summarized the changes in human sleep under extreme environments to help gain a better understanding of the mechanisms by which these specific environments impact human sleep. It is expected that this review will provide a solid theoretical foundation for optimizing long-term survival strategies in extreme environments and help humans adapt to and overcome the challenges posed by extreme environments more effectively.

Decision-Making and Risk-Propensity Changes during and after the COVID-19 Pandemic Lockdown

The imposition of lockdowns during the COVID-19 pandemic placed individuals under conditions of environmental stress, threatening individual and collective wellbeing. This study aimed to investigate the temporal effects of isolation and confinement during and after the Italian lockdown on decision-making, risk propensity, and cognitive control processes. The present study covered almost the entire Italian lockdown period (each week from the end of March to mid-May 2020), plus a follow-up measure (September 2020). At each time-point, respondents completed online behavioral tasks, which involved measuring risk-propensity (Balloon Analogue Risk Task), decision-making (Iowa Gambling Task), and cognitive flexibility (Category Switch Task). They also filled in questionnaires regarding subjective stress and anxiety. The main findings showed that the decision-making abilities of the respondents were affected as the confinement progressed. Furthermore, individuals who were more subjectively impacted by the lockdown/isolation experience exhibited impaired decision-making, especially during the lockdown. The results of the study highlight that prolonged confinement may affect human decision making, and help understand individuals' misbehaviors during emergencies and develop effective countermeasures aimed at reducing the burden of the healthcare system.

Prospective Use of Probiotics to Maintain Astronaut Health during Spaceflight

Maintaining an astronaut's health during space travel is crucial. Multiple studies have observed various changes in the gut microbiome and physiological health. Astronauts on board the International Space Station (ISS) had changes in the microbial communities in their gut, nose, and skin. Additionally, immune system cell alterations have been observed in astronauts with changes in neutrophils, monocytes, and T-cells. Probiotics help tackle these health issues caused during spaceflight by inhibiting pathogen adherence, enhancing epithelial barrier function by reducing permeability, and producing an anti-inflammatory effect. When exposed to microgravity, probiotics demonstrated a shorter lag phase, faster growth, improved acid tolerance, and bile resistance. A freeze-dried Lactobacillus casei strain Shirota capsule was tested for its stability on ISS for a month and has been shown to enhance innate immunity and balance intestinal microbiota. The usage of freeze-dried spores of B. subtilis proves to be advantageous to long-term spaceflight because it qualifies for all the aspects tested for commercial probiotics under simulated conditions. These results demonstrate a need to further study the effect of probiotics in simulated microgravity and spaceflight conditions and to apply them to overcome the effects caused by gut microbiome dysbiosis and issues that might occur during spaceflight.

How Sleep Research in Extreme Environments Can Inform the Military: Advocating for a Transactional Model of Sleep Adaptation

PURPOSE OF REVIEW

We review the literature on sleep in extreme environments. Accordingly, we present a model that identifies the need for mitigating interventions to preserve sleep quality for military deployments.

RECENT FINDINGS

Situational factors that affect sleep in extreme environments include cold temperatures, isolated and confined areas, fluctuating seasonality, photoperiodicity, and extreme latitudes and altitudes. Results vary across studies, but general effects include decreased total sleep time, poor sleep efficiency, and non-specific phase delays or phase advances in sleep onset and sleep architecture. Considering habitability measures (e.g., light or temperature control) and individual differences such as variable stress responses or sleep need can mitigate these effects to improve mood, cognition, and operational performance. Although the situational demands during military missions inevitably reduce total sleep time and sleep efficiency, mitigating factors can attenuate sleep-related impairments, hence allowing for optimal mission success and personnel safety.

Short-term isolation effects on the brain, cognitive performance, and sleep-The role of exercise

Isolation is stressful and negatively affects sleep and mood and might also affect the structure and function of the brain. Physical exercise improves brain function. We investigated the influence of physical exercise during isolation on sleep, affect, and neurobehavioral function. N = 16 were isolated for 30 days with daily exercise routines (ISO₁₀₀) and n = 16 isolated for 45 days with every second day exercise (ISO₅₀). N = 27 were non-isolated controls who either exercised on a daily basis (CTRL_Ex) or refused exercise (CTRL_NonEx) for 30 days. At the beginning and the end of each intervention, intravenous morning cortisol, melatonin, brain-derived neurotrophic factor and IGF-1, positive and negative affect scales, electroencephalography, cognitive function, and sleep patterns (actigraphy) were assessed. High levels of cortisol were observed for the isolated groups (p < .05) without negative effects on the brain, cognitive function, sleep, and mood after 4 to 6 weeks of isolation, where physical exercise was performed regularly. An increase in cortisol and impairments of sleep quality, mood, cognitive function, and neurotrophic factors (p < .05) were observed after 4 weeks of absence of physical exercise in the CTRL_NonEx group. These findings raise the assumption that regular physical exercise routines are a key component during isolation to maintain brain health and function.

Living on the edge: How to prepare for it?

Introduction

Isolated, confined, and extreme (ICE) environments such as found at Antarctic, Arctic, and other remote research stations are considered space-analogs to study the long duration isolation aspects of operational space mission conditions.

Methods

We interviewed 24 sojourners that participated in different short/long duration missions in an Antarctic (Concordia, Halley VI, Rothera, Neumayer II) or non-Antarctic (e.g., MDRS, HI-SEAS) station or in polar treks, offering a unique insight based on first-hand information on the nature of demands by ICE-personnel at multiple levels of functioning. We conducted a qualitative thematic analysis to explore how sojourners were trained, prepared, how they experienced the ICE-impact in function of varieties in environment, provided trainings, station-culture, and type of mission.

Results

The ICE-environment shapes the impact of organizational, interpersonal, and individual working- and living systems, thus influencing the ICE-sojourners' functioning. Moreover, more specific training for operating in these settings would be beneficial. The identified pillars such as sensory deprivation, sleep, fatigue, group dynamics, displacement of negative emotions, gender-issues along with coping strategies such as positivity, salutogenic effects, job dedication and collectivistic thinking confirm previous literature. However, in this work, we applied a systemic perspective, assembling the multiple levels of functioning in ICE-environments.

Discussion

A systemic approach could serve as a guide to develop future preparatory ICE-training programs, including all the involved parties of the crew system (e.g., family, on-ground crew) with attention for the impact of organization- and station-related subcultures and the risk of unawareness about the impact of poor sleep, fatigue, and isolation on operational safety that may occur on location.

Sleep loss effects on physiological and cognitive responses to systemic environmental hypoxia

In the course of their missions or training, alpinists, but also mountain combat forces and mountain security services, professional miners, aircrew, aircraft and glider pilots and helicopter crews are regularly exposed to altitude without oxygen supplementation. At altitude, humans are exposed to systemic environmental hypoxia induced by the decrease in barometric pressure (<1,013 hPa) which decreases the inspired partial pressure of oxygen (PIO₂), while the oxygen fraction is constant (equal to approximately 20.9%). Effects of altitude on humans occur gradually and depend on the duration of exposure and the altitude level. From 1,500 m altitude (response threshold), several adaptive responses offset the effects of hypoxia, involving the respiratory and the cardiovascular systems, and the oxygen transport capacity of the blood. Fatigue and cognitive and sensory disorders are usually observed from 2,500 m (threshold of prolonged hypoxia). Above 3,500 m (the threshold for disorders), the effects are not completely compensated and maladaptive responses occur and individuals develop altitude headache or acute altitude illness [Acute Mountain Sickness (AMS)]. The magnitude of effects varies considerably between different physiological systems and exhibits significant inter-individual variability. In addition to comorbidities, the factors of vulnerability are still little known. They can be constitutive (genetic) or circumstantial (sleep deprivation, fatigue, speed of ascent.). In particular, sleep loss, a condition that is often encountered in real-life settings, could have an impact on the physiological and cognitive responses to hypoxia. In this review, we report the current state of knowledge on the impact of sleep loss on responses to environmental hypoxia in humans, with the aim of identifying possible consequences for AMS risk and cognition, as well as the value of behavioral and non-pharmacological countermeasures.

To infinity and beyond: Strategies for fabricating medicines in outer space

Recent advancements in next generation spacecrafts have reignited public excitement over life beyond Earth. However, to safeguard the health and safety of humans in the hostile environment of space, innovation in pharmaceutical manufacturing and drug delivery deserves urgent attention. In this review/commentary, the current state of medicines provision in space is explored, accompanied by a forward look on the future of pharmaceutical manufacturing in outer space. The hazards associated with spaceflight, and their corresponding medical problems, are first briefly discussed. Subsequently, the infeasibility of present-day medicines provision systems for supporting deep space exploration is examined. The existing knowledge gaps on the altered clinical effects of medicines in space are evaluated, and suggestions are provided on how clinical trials in space might be conducted. An envisioned model of on-site production and delivery of medicines in space is proposed, referencing emerging technologies (e.g. Chemputing, synthetic biology, and 3D printing) being developed on Earth that may be adapted for extra-terrestrial use. This review concludes with a critical analysis on the regulatory considerations necessary to facilitate the adoption of these technologies and proposes a framework by which these may be enforced. In doing so, this commentary aims to instigate discussions on the pharmaceutical needs of deep space exploration, and strategies on how these may be met.

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Space is a hostile environment that threatens human health and drug stability.

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Data on the behaviour of medicines in space is critical but lacking.

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Novel drug manufacturing and delivery strategies are needed to safeguard crewmembers’ safety.

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Chemputing, synthetic biology, and 3D printing are examples of such emerging technologies.

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A regulatory framework for space medicines must be implemented to assure quality.

Comprehensive detrimental effects of a simulated frequently shifting schedule on diurnal rhythms and vigilance

Accumulating data have demonstrated that shift work causes a disturbance in circadian rhythms, which is detrimental to physiology and performance. However, the detailed effects of shift work and especially the underlying mechanisms remain to be further investigated. Frequently shifting schedules are widely used in industries, e.g., maritime tasks, oil mining, and aviation. In this work, we investigated the physiological changes and vigilance of 12 subjects who lived on a 30-day frequent shift working schedule in a confined environment, which mimics the common maritime schedules. Elevated and decreased cortisol levels were observed at different stages during the shift, suggesting the occurrence of stress and fatigue. The results of the Karolinska Sleepiness Scale (KSS) indicate increased sleepiness and a changed pattern of the rhythmicity of sleepiness during the shift. The tests of the Psychomotor Vigilance Task (PVT) reveal that the shift led to a continuously decreasing alertness as the shift working schedule progressed, which is prevalently due to the increasingly slower reaction speed. The PVT time-out errors were significantly increased in the early period but decreased in the late period. In addition, we found recoupling of the correlations between multiple physiological and cognitive variables. For instance, heartbeat rate (HR) and breath rate (BR) showed moderate correlations in the control and early periods but little in the late period. Together, these results reveal substantial alterations in diurnal rhythms, affected vigilance and changed coupling of the correlations of diurnal rhythms, physiology and cognition caused by a shift schedule. Our findings may help in the recognition of the detrimental effects of such working schedules and provide clues for the development of potential mitigations.

Monitoring the Impact of Spaceflight on the Human Brain

Extended exposure to radiation, microgravity, and isolation during space exploration has significant physiological, structural, and psychosocial effects on astronauts, and particularly their central nervous system. To date, the use of brain monitoring techniques adopted on Earth in pre/post-spaceflight experimental protocols has proven to be valuable for investigating the effects of space travel on the brain. However, future (longer) deep space travel would require some brain function monitoring equipment to be also available for evaluating and monitoring brain health during spaceflight. Here, we describe the impact of spaceflight on the brain, the basic principles behind six brain function analysis technologies, their current use associated with spaceflight, and their potential for utilization during deep space exploration. We suggest that, while the use of magnetic resonance imaging (MRI), positron emission tomography (PET), and computerized tomography (CT) is limited to analog and pre/post-spaceflight studies on Earth, electroencephalography (EEG), functional near-infrared spectroscopy (fNIRS), and ultrasound are good candidates to be adapted for utilization in the context of deep space exploration.

The submariners' sleep study. A field investigation of sleep and circadian hormones during a 67-days submarine mission with a strict 6h-on/6h-off watch routine

The submarine working and living environment is an isolated, confined, and extreme (ICE) environment where a continuous on-watch is required to fulfill the tactical objectives. The current study examined whether a physiological and behavioral adjustment to an operational watch standing scheme occurred in terms of hormonal secretion (i.e., melatonin and cortisol) and sleep during a 67-days undersea mission. The crew followed a strict scheme of watch-on blocks at 0:00-06:00 h and at 12:00-18:00 h (group 1, diurnal sleep group) or watch-on blocks at 06:00-12:00 h and 18:00-24:00 h (group 2, nocturnal sleep group). We sampled saliva during the operational blocks over a 24h period at day 55 of the mission and collected sleep actigraphy data during the entire mission in 10 participants. Sleep showed a biphasic split pattern with significantly unequal distributions of total sleep time (TST) and sleep efficiency (SE) between the two sleeping blocks, i.e., one long and one short sleep bout. Melatonin secretion showed no adjustment at the end of the mission to the watch standing blocks, following an endogenous circadian rhythm independent from the social zeitgebers with indications of a phase shift. Cortisol secretion however matched the biphasic work-sleep shift routine. Human physiology does not fully obey operational needs and there are differences in adjustment between melatonin and cortisol. A watch standing schedule that provides a balance between physiology and operationality still needs to be established. The potential adaptation effects of bright light therapy and melatonin supplementation should be investigated in future research.