title: Sleeping under the Ocean: Despite Total Isolation, Nuclear Submariners Maintain Their Sleep and Wake Patterns throughout Their Under Sea Mission.
abstract: BACKGROUND
  To assess the effects of isolation, inadequate exposure to light and specific shift work on the subjective and objective measurements of sleep and alertness of submariners.
  
  
  OBJECTIVE
  A strictly controlled randomized crossover study with the polysomnography recorded twice during the mission.
  
  
  METHODS
  Setting: Shift and night work with prolonged (70 days) social isolation from the real world (with no phone or Internet contact with families or friends during a routine mission aboard the "Téméraire" French Strategic Submarine with Ballistic Nuclear missiles (SSBN). Participants: 19 submariners working on a 24-hour shift for three days in a row schedule. Interventions: The participants attended two polysomnographic (PSG) recordings of night sleep on Day 21 (D21) and Day 51 (D51) of the 70-day patrol; urine cortisol levels were also taken after sleep, and subjective assessments of sleep, sleepiness, mood and anxiety on D21 and D51. The light and temperature on board were also recorded.
  
  
  RESULTS
  PSG analyses showed that sleep did not significantly vary in length (total sleep time) or in quality between D21 and D51. The mariners reported the same subjective sleep, sleepiness, anxiety or mood (except for a slightly worse score for confusion on D51). Blood cortisol levels did not vary significantly.
  
  
  CONCLUSIONS
  These results show that humans living in an isolated environment for more than two months with this specific shift schedule do not suffer from any significant effects on sleep, sleepiness and confusion between D21 and D51, when they follow an organized regular shift pattern with controlled light and temperature.
authors.affiliation: Institut de recherche biomédicale des armées (IRBA), Unité Stress, Brétigny-sur-Orge, France.
authors.forename: Marion
authors.initials: M
authors.lastname: Trousselard
authors.affiliation: Université Paris Descartes, Sorbonne Paris Cité, APHP, Hôtel-Dieu, Centre du sommeil et de la vigilance, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Equipe d'accueil VIgilance FAtigue SOMmeil (VIFASOM) et santé publique EA 7330, Paris, France.
authors.forename: Damien
authors.initials: D
authors.lastname: Leger
authors.affiliation: Université Paris Descartes, Sorbonne Paris Cité, Equipe d'accueil VIgilance FAtigue SOMmeil (VIFASOM) et santé publique EA 7330, Paris, France; Institut de recherche biomédicale des armées (IRBA), Unité Fatigue et Vigilance, Brétigny-sur-Orge, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: van Beers
authors.affiliation: HIA Desgenettes, Unité sommeil, Lyon, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Coste
authors.affiliation: Escadrille des Sous marins lanceurs d'engins (SNLE), Service médical de l'ESNLE, Brest, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Vicard
authors.affiliation: Escadrille des Sous marins lanceurs d'engins (SNLE), Service médical de l'ESNLE, Brest, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Pontis
authors.affiliation: Escadrille des Sous marins lanceurs d'engins (SNLE), Service médical de l'ESNLE, Brest, France.
authors.forename: Sylvain-Nicolas
authors.initials: SN
authors.lastname: Crosnier
authors.affiliation: Université Paris Descartes, Sorbonne Paris Cité, Equipe d'accueil VIgilance FAtigue SOMmeil (VIFASOM) et santé publique EA 7330, Paris, France; Institut de recherche biomédicale des armées (IRBA), Unité Fatigue et Vigilance, Brétigny-sur-Orge, France.
authors.forename: Mounir
authors.initials: M
authors.lastname: Chennaoui
mesh_terms: D000328:Adult; D000339:Affect; D018592:Cross-Over Studies; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D008297:Male; D008875:Middle Aged; D008889:Military Personnel; D017286:Polysomnography; D012767:Ships; D012890:Sleep / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology*
chemical_list: D006854:Hydrocortisone