title: Learning to live on a Mars day: fatigue countermeasures during the Phoenix Mars Lander mission.
abstract: OBJECTIVE
  To interact with the robotic Phoenix Mars Lander (PML) spacecraft, mission personnel were required to work on a Mars day (24.65 h) for 78 days. This alien schedule presents a challenge to Earth-bound circadian physiology and a potential risk to workplace performance and safety. We evaluated the acceptability, feasibility, and effectiveness of a fatigue management program to facilitate synchronization with the Mars day and alleviate circadian misalignment, sleep loss, and fatigue.
  
  
  METHODS
  Operational field study.
  
  
  METHODS
  PML Science Operations Center.
  
  
  METHODS
  Scientific and technical personnel supporting PML mission.
  
  
  METHODS
  Sleep and fatigue education was offered to all support personnel. A subset (n = 19) were offered a short-wavelength (blue) light panel to aid alertness and mitigate/reduce circadian desynchrony. They were assessed using a daily sleep/work diary, continuous wrist actigraphy, and regular performance tests. Subjects also completed 48-h urine collections biweekly for assessment of the circadian 6-sulphatoxymelatonin rhythm.
  
  
  RESULTS
  Most participants (87%) exhibited a circadian period consistent with adaptation to a Mars day. When synchronized, main sleep duration was 5.98 ± 0.94 h, but fell to 4.91 ± 1.22 h when misaligned (P < 0.001). Self-reported levels of fatigue and sleepiness also significantly increased when work was scheduled at an inappropriate circadian phase (P < 0.001). Prolonged wakefulness (≥ 21 h) was associated with a decline in performance and alertness (P < 0.03 and P < 0.0001, respectively).
  
  
  CONCLUSIONS
  The ability of the participants to adapt successfully to the Mars day suggests that future missions should utilize a similar circadian rhythm and fatigue management program to reduce the risk of sleepiness-related errors that jeopardize personnel safety and health during critical missions.
authors.affiliation: Division of Sleep Medicine, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA. lkbarger@hms.harvard.edu
authors.forename: Laura K
authors.initials: LK
authors.lastname: Barger
authors.forename: Jason P
authors.initials: JP
authors.lastname: Sullivan
authors.forename: Andrea S
authors.initials: AS
authors.lastname: Vincent
authors.forename: Edna R
authors.initials: ER
authors.lastname: Fiedler
authors.forename: Laurence M
authors.initials: LM
authors.lastname: McKenna
authors.forename: Erin E
authors.initials: EE
authors.lastname: Flynn-Evans
authors.forename: Kirby
authors.initials: K
authors.lastname: Gilliland
authors.forename: Walter E
authors.initials: WE
authors.lastname: Sipes
authors.forename: Peter H
authors.initials: PH
authors.lastname: Smith
authors.forename: George C
authors.initials: GC
authors.lastname: Brainard
authors.forename: Steven W
authors.initials: SW
authors.lastname: Lockley
mesh_terms: D056044:Actigraphy; D000328:Adult; D002940:Circadian Rhythm / Q000502:physiology*; D005221:Fatigue / Q000209:etiology / Q000517:prevention & control*; D005260:Female; D006801:Humans; D008297:Male; D018535:Mars; D009483:Neuropsychological Tests; D010789:Phototherapy / Q000379:methods; D011597:Psychomotor Performance / Q000502:physiology; D012890:Sleep / Q000502:physiology; D012892:Sleep Deprivation / Q000503:physiopathology / Q000628:therapy; D014940:Work Schedule Tolerance / Q000502:physiology / Q000523:psychology