title: How stressful are 105 days of isolation? Sleep EEG patterns and tonic cortisol in healthy volunteers simulating manned flight to Mars.
abstract: Spaceflights "environment" negatively affects sleep and its functions. Among the different causes promoting sleep alterations, such as circadian rhythms disruption and microgravity, stress is of great interest also for earth-based sleep medicine. This study aims to evaluate the relationships between stress related to social/environmental confinement and sleep in six healthy volunteers involved in the simulation of human flight to Mars (MARS500). Volunteers were sealed in a spaceship simulator for 105 days and studied at 5 specific time-points of the simulation period. Sleep EEG, urinary cortisol (24 h preceding sleep EEG recording) and subjectively perceived stress levels were collected. Cognitive abilities and emotional state were evaluated before and after the simulation. Sleep EEG parameters in the time (latency, duration) and frequency (power and hemispheric lateralization) domains were evaluated. Neither cognitive and emotional functions alterations nor abnormal stress levels were found. Higher cortisol levels were associated to: (i) decrease of sleep duration, increase of arousals, and shortening of REM latency; (ii) reduction of delta power and enhancement of sigma and beta in NREM N3; and (iii) left lateralization of delta activity (NREM and REM) and right lateralization of beta activity (NREM). Stressful conditions, even with cortisol fluctuations in the normal range, alter sleep structure and sleep EEG spectral content, mirroring pathological conditions such as primary insomnia or insomnia associated to depression. Correlations between cortisol fluctuations and sleep changes suggest a covert risk for developing allostatic load, and thus the need to develop ad-hoc countermeasures for preventing sleep alterations in long lasting manned space missions.
authors.affiliation: Department of Surgery, Medical, Molecular and Critical Area Pathology, University of Pisa, via Paradisa 2, 56124 Pisa, Italy; EXTREME Centre, Scuola Superiore Sant'Anna, Piazza Martiri della Libertà 33, 56127 Pisa, Italy; Institute of Clinical Physiology, National Research Council (CNR), via Moruzzi 1, 56124 Pisa, Italy. Electronic address: gemignan@dfb.unipi.it.
authors.forename: Angelo
authors.initials: A
authors.lastname: Gemignani
authors.affiliation: Perceptual Robotics Laboratory, Scuola Superiore Sant'Anna, Pisa, via Alamanni 13b, 56010 Pisa, Italy; EXTREME Centre, Scuola Superiore Sant'Anna, Piazza Martiri della Libertà 33, 56127 Pisa, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Piarulli
authors.affiliation: EXTREME Centre, Scuola Superiore Sant'Anna, Piazza Martiri della Libertà 33, 56127 Pisa, Italy; Institute of Clinical Physiology, National Research Council (CNR), via Moruzzi 1, 56124 Pisa, Italy.
authors.forename: Danilo
authors.initials: D
authors.lastname: Menicucci
authors.affiliation: Department of Surgery, Medical, Molecular and Critical Area Pathology, University of Pisa, via Paradisa 2, 56124 Pisa, Italy; EXTREME Centre, Scuola Superiore Sant'Anna, Piazza Martiri della Libertà 33, 56127 Pisa, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Laurino
authors.affiliation: Laboratory of Clinical Biochemistry and Molecular Biology, Department of Experimental Pathology, Medical Biotechnologies, Infectivology and Epidemiology, University of Pisa, via Roma 67, 56126, Pisa, Italy.
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Rota
authors.affiliation: EXTREME Centre, Scuola Superiore Sant'Anna, Piazza Martiri della Libertà 33, 56127 Pisa, Italy; Institute of Clinical Physiology, National Research Council (CNR), via Moruzzi 1, 56124 Pisa, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Mastorci
authors.affiliation: Institute of Biomedical Problems of Moscow, Moscow, Russia.
authors.forename: Vadim
authors.initials: V
authors.lastname: Gushin
authors.affiliation: Institute of Biomedical Problems of Moscow, Moscow, Russia.
authors.forename: Olga
authors.initials: O
authors.lastname: Shevchenko
authors.affiliation: EXTREME Centre, Scuola Superiore Sant'Anna, Piazza Martiri della Libertà 33, 56127 Pisa, Italy.
authors.forename: Erika
authors.initials: E
authors.lastname: Garbella
authors.affiliation: EXTREME Centre, Scuola Superiore Sant'Anna, Piazza Martiri della Libertà 33, 56127 Pisa, Italy; Institute of Clinical Physiology, National Research Council (CNR), via Moruzzi 1, 56124 Pisa, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Pingitore
authors.affiliation: Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Sebastiani
authors.affiliation: Perceptual Robotics Laboratory, Scuola Superiore Sant'Anna, Pisa, via Alamanni 13b, 56010 Pisa, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Bergamasco
authors.affiliation: EXTREME Centre, Scuola Superiore Sant'Anna, Piazza Martiri della Libertà 33, 56127 Pisa, Italy; Institute of Clinical Physiology, National Research Council (CNR), via Moruzzi 1, 56124 Pisa, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: L'Abbate
authors.affiliation: EXTREME Centre, Scuola Superiore Sant'Anna, Piazza Martiri della Libertà 33, 56127 Pisa, Italy; Institute of Clinical Physiology, National Research Council (CNR), via Moruzzi 1, 56124 Pisa, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Allegrini
authors.affiliation: EXTREME Centre, Scuola Superiore Sant'Anna, Piazza Martiri della Libertà 33, 56127 Pisa, Italy; Institute of Clinical Physiology, National Research Council (CNR), via Moruzzi 1, 56124 Pisa, Italy.
authors.forename: Remo
authors.initials: R
authors.lastname: Bedini
mesh_terms: D000328:Adult; D058256:Brain Waves / Q000502:physiology*; D003071:Cognition / Q000502:physiology; D004569:Electroencephalography; D004644:Emotions; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D025341:Principal Component Analysis; D012890:Sleep / Q000502:physiology*; D012934:Social Isolation / Q000523:psychology*; D018561:Space Simulation; D013315:Stress, Psychological / Q000503:physiopathology*; D013997:Time Factors
keywords: Cortisol; High-density EEG; MARS 500; NREM sleep; Sleep; Social/environmental confinement; Stress