SLEEP

Olivier, Mairesse,;Eoin, Macdonald-Nethercott,;Daniel, Neu,;Helio, Fernandez Tellez,;Emilie, Dessy,;Xavier, Neyt,;Romain, Meeusen,;Nathalie, Pattyn,

doi: 10.1093/sleep/zsy206pmid: 30403819

Abstract Study Objectives Manned spaceflights from Earth to Mars will likely become reality within the next decades. Humans will be exposed to prolonged isolation, confinement, and altered photoperiods in artificial atmospheric conditions, with potential adverse effects on sleep and performance. On Earth, polar environments serve as space-analogues to study human adaptation, yet few studies include polysomnography due to operational constraints. Methods Polysomnography, subjective sleepiness and fatigue and psychomotor performance were measured every six weeks in 13 males (“Hivernauts”) during a 13-month winter-over campaign at Concordia (Antarctica). Stability and robustness of inter-individual differences were examined by means of intra-class correlations. Results Hivernauts present with high-altitude periodic breathing, increased sleep onset latencies and reduced psychomotor speed. Except for obstructive apneas, all sleep, sleepiness and psychomotor performance variables remain stable over time. Individual differences in respiratory variables show the highest degree of stability and robustness, followed by fatigue and situational sleepiness, sleep fragmentation and psychomotor speed, suggesting moderate to substantial trait-like characteristics for these variables. Phase-delays are suspected in Hivernauts, both in individuals with imposed and self-selected bedtimes. A significant decline in psychomotor speed over time is observed in the latter group. Conclusions Space-analog conditions such as isolated confinement, extreme photoperiods and altered atmospheric conditions affect human sleep and performance. However, individual responses to these extreme environmental challenges show large differences and remain relatively stable under prolonged exposure. Ad hoc polysomnographic, including respiratory function monitoring is therefore recommended for selecting eligible candidates for extra-terrestrial sojourns. Mars, Antarctica, altered photoperiods, altitude, hypoxia, winter-over, space, periodic breathing, trait, individual differences © Sleep Research Society 2018. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail [email protected]. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Mélanie, Strauss,;Stanislas, Dehaene,

doi: 10.1093/sleep/zsy232pmid: 30476318

Abstract Can the sleeping brain develop predictions of future auditory stimuli? Past research demonstrated disrupted prediction capabilities during sleep in the context of novel, arbitrary auditory sequences, but the availability of over-learned knowledge already stored in long-term memory could still be preserved. We tested the sleeping brain capabilities to detect violations of simple arithmetic facts. Sleeping subjects were presented with spoken arithmetic facts such as “two plus two is nine” and brain responses to correct or incorrect results were recorded in electro and magneto-encephalography. Sleep responses were compared to both attentive and inattentive wakefulness. During attentive wakefulness, arithmetic violations elicited a succession of N400 and P600 effects, while no such activations could be recorded in sleep or in inattentive wakefulness. Still, small but significant effects remained in sleep, advocating for a preserved but partial accessibility to arithmetic facts stored in long-term memory and preserved predictions of low-level and already learned knowledge. Those effects were very different from residual activities seen in inattention, highlighting the differences of information processing between the sleeping and the inattentive brain. Arithmetic, N400, P600, Sleep, EEG, MEG, Consciousness, Predictive coding © Sleep Research Society 2018. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail [email protected]. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)