title: Altitude and seasonality impact on sleep in Antarctica.
abstract: BACKGROUND
  This study investigates the effects of seasonality and altitude on sleep in extreme Antarctic conditions.
  
  
  METHODS
  During summer and winter periods, 24 h of actimetric recordings were obtained at two different research stations, Dumont d'Urville (sea level altitude) and Concordia (corrected altitude 12,467 ft or 3800 m).
  
  
  RESULTS
  During daytime, there were no altitude- or season-related differences in time spent at work, energy expenditure, or number of walking steps. During the nighttime however, total sleep time was longer (m = 427.4; SD = 42.4), sleep efficiency higher (m = 90; SD = 4.8), and wake after sleep onset shorter (m = 42.2; SD = 28.7) at sea level. Additionally, sleep fragmentation episodes and energy expenditure were higher during summer than winter periods.
  
  
  CONCLUSIONS
  Our results show that dramatic variations in light exposure are not the only main factor affecting sleep quality in Antarctica, as altitude also markedly impacted sleep in these conditions. The effect of altitude-induced hypoxia should be taken into account in future investigations of sleep in extreme environments.
authors.forename: Gregory
authors.initials: G
authors.lastname: Collet
authors.forename: Olivier
authors.initials: O
authors.lastname: Mairesse
authors.forename: Aisha
authors.initials: A
authors.lastname: Cortoos
authors.forename: Helio Fernandez
authors.initials: HF
authors.lastname: Tellez
authors.forename: Xavier
authors.initials: X
authors.lastname: Neyt
authors.forename: Philippe
authors.initials: P
authors.lastname: Peigneux
authors.forename: Eoin
authors.initials: E
authors.lastname: Macdonald-Nethercott
authors.forename: Yves-Marie
authors.initials: YM
authors.lastname: Ducrot
authors.forename: Nathalie
authors.initials: N
authors.lastname: Pattyn
mesh_terms: D000328:Adult; D000531:Altitude; D000864:Antarctic Regions; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D008297:Male; D012621:Seasons; D012893:Sleep Wake Disorders / Q000209:etiology*