title: Prolonged sleep under Stone Age conditions.
abstract: OBJECTIVE
  We report on a unique experiment designed to investigate the impact of prehistoric living conditions on sleep-wake behavior.
  
  
  METHODS
  A group of five healthy adults were assessed during life in a Stone Age-like settlement over two months.
  
  
  RESULTS
  The most notable finding was that nocturnal time in bed and estimated sleep time, as measured by actigraphy, markedly increased during the experimental period compared to the periods prior to and following the experiment. These increases were primarily driven by a phase-advance shift of sleep onset. Subjective assessments of health and functioning did not reveal any relevant changes across the study.
  
  
  CONCLUSIONS
  Our observations provide further evidence for the long-held belief that the absence of modern living conditions is associated with an earlier sleep phase and prolonged sleep duration.
  
  
  CONCLUSIONS
  A commentary on this article appears in this issue on page 723.
authors.affiliation: Department of Psychiatry and Psychotherapy, University Medical Center Freiburg, Germany.
authors.forename: Hannah
authors.initials: H
authors.lastname: Piosczyk
authors.affiliation: Department of Psychiatry and Psychotherapy, University Medical Center Freiburg, Germany.
authors.forename: Nina
authors.initials: N
authors.lastname: Landmann
authors.affiliation: Department of Psychiatry and Psychotherapy, University Medical Center Freiburg, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Holz
authors.affiliation: Department of Psychiatry and Psychotherapy, University Medical Center Freiburg, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Feige
authors.affiliation: Department of Psychiatry and Psychotherapy, University Medical Center Freiburg, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Riemann
authors.affiliation: Department of Psychiatry and Psychotherapy, University Medical Center Freiburg, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Nissen
authors.affiliation: Department of Psychiatry and Psychotherapy, University Medical Center Freiburg, Germany ; Schoen Clinic Roseneck, Prien am Chiemsee, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Voderholzer
mesh_terms: D056044:Actigraphy / Q000379:methods; D000328:Adult; D002940:Circadian Rhythm; D005260:Female; D005858:Germany; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D012890:Sleep / Q000502:physiology*; D011795:Surveys and Questionnaires; D013997:Time Factors
keywords: Stone Age; sleep; sleep duration; sleepless society