Psychological and Behavioral Changes during Confinement in a 520-Day Simulated Interplanetary Mission to Mars Mathias Basner 1 *, David F. Dinges 1 , Daniel J. Mollicone 2 , Igor Savelev 3,4 , Adrian J. Ecker 1 , Adrian Di Antonio 1 , Christopher W. Jones 1 , Eric C. Hyder 1 , Kevin Kan 2 , Boris V. Morukov 5 , Jeffrey P. Sutton 4,6 1 Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America, 2 Pulsar Informatics, Philadelphia, Pennsylvania, United States of America, 3 Wyle, Houston, Texas, United States of America, 4 National Space Biomedical Research Institute, Houston, Texas, United States of America, 5 Institute for Biomedical Problems, Moscow, Russia, 6 Center for Space Medicine and Department of Medicine, Baylor College of Medicine, Houston, Texas, United States of America Abstract Behavioral health risks are among the most serious and difficult to mitigate risks of confinement in space craft during long- duration space exploration missions. We report on behavioral and psychological reactions of a multinational crew of 6 healthy males confined in a 550 m 3 chamber for 520 days during the first Earth-based, high-fidelity simulated mission to Mars. Rest-activity of crewmembers was objectively measured throughout the mission with wrist-worn actigraphs. Once weekly throughout the mission crewmembers completed the Beck Depression Inventory-II (BDI-II), Profile of Moods State short form (POMS), conflict questionnaire, the Psychomotor Vigilance Test (PVT-B), and series of visual analogue scales on stress and fatigue. We observed substantial inter-individual differences in the behavioral responses of crewmembers to the prolonged mission confinement and isolation. The crewmember with the highest average POMS total mood disturbance score throughout the mission also reported symptoms of depression in 93% of mission weeks, which reached mild-to- moderate levels in .10% of mission weeks. Conflicts with mission control were reported five times more often than conflicts among crewmembers. Two crewmembers who had the highest ratings of stress and physical exhaustion accounted for 85% of the perceived conflicts. One of them developed a persistent sleep onset insomnia with ratings of poor sleep quality, which resulted in chronic partial sleep deprivation, elevated ratings of daytime tiredness, and frequent deficits in behavioral alertness. Sleep-wake timing was altered in two other crewmembers, beginning in the first few months of the mission and persisting throughout. Two crewmembers showed neither behavioral disturbances nor reports of psychological distress during the 17-month period of mission confinement. These results highlight the importance of identifying behavioral, psychological, and biological markers of characteristics that predispose prospective crewmembers to both effective and ineffective behavioral reactions during the confinement of prolonged spaceflight, to inform crew selection, training, and individualized countermeasures. Citation: Basner M, Dinges DF, Mollicone DJ, Savelev I, Ecker AJ, et al. (2014) Psychological and Behavioral Changes during Confinement in a 520-Day Simulated Interplanetary Mission to Mars. PLoS ONE 9(3): e93298. doi:10.1371/journal.pone.0093298 Editor: Nandu Goswami, Medical University of Graz, Austria Received October 3, 2013; Accepted February 9, 2014; Published March 27, 2014 Copyright: ß 2014 Basner et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: The research was supported by the National Space Biomedical Research Institute (NSBRI) through NASA NCC 9-58, and by the Institute for Experimental Psychiatry Research Foundation. The funders had no role in study design, data collection and analysis, and decision to publish. Jeffrey Sutton is President, CEO and Institute Director of NSBRI. He helped in the preparation of the manuscript. The Friedkin Chair for Research in Sensory System Integration and Space Medicine to Jeffrey Sutton is also acknowledged. Competing Interests: Jeffrey P. Sutton and Mathias Basner are PLOS ONE editorial board members. Daniel Mollicone is CEO of Pulsar Informatics Inc. and Igor Savelev was employed by Wyle at the time the authors performed the study. This does not alter the authors’ adherence to all the PLOS ONE policies on sharing data and materials. * E-mail: basner@upenn.edu Introduction With the completion of the International Space Station (ISS) and expanding multinational involvement in space flight, the first human interplanetary mission to Mars is anticipated during this century. Using conventional propulsion and accounting for celestial mechanics, a round trip of 520 days is a standard reference mission. This timeframe is well beyond the duration astronauts and cosmonauts have remained confined either in a spacecraft or in a high-fidelity spaceflight simulation on Earth. Current missions on ISS are 6 months in duration. Only 4 people have spent more than 1 year in a spacecraft, with the record for continuous confinement set by Valery Polyakov at 437 days on Mir. The longest Earth-based space flight simulation (SFINCSS- 99) involved 4 Russians confined in connected hyperbaric chambers for 240 consecutive days (one crewmember was confined for 263 days) [1–3]. Due to communication delays, a Mars mission will also require greater crew autonomy than currently experienced in spaceflight [4]. A U.S. National Academies report on astronaut care for exploration missions concluded that behavioral and mental health issues will be increasingly important during such missions, which will likely involve a crew varying in social and cultural backgrounds. The report urged research focus on the behavior of astronauts in extreme, isolated microenvironments such as inside spacecraft [5]. PLOS ONE | www.plosone.org 1 March 2014 | Volume 9 | Issue 3 | e93298