title: Sleep Strengthens but does Not Reorganize Memory Traces in a Verbal Creativity Task.
abstract: OBJECTIVE
  Sleep after learning promotes the quantitative strengthening of new memories. Less is known about the impact of sleep on the qualitative reorganization of memory content. This study tested the hypothesis that sleep facilitates both memory strengthening and reorganization as indexed by a verbal creativity task.
  
  
  METHODS
  Sixty healthy university students (30 female, 30 male, 20-30 years) were investigated in a randomized, controlled parallel-group study with three experimental groups (sleep, sleep deprivation, daytime wakefulness). At baseline, 60 items of the Compound Remote Associate (CRA) task were presented. At retest after the experimental conditions, the same items were presented again together with 20 new control items to disentangle off-line incubation from online performance effects.
  
  
  RESULTS
  Sleep significantly strengthened formerly encoded memories in comparison to both wake conditions (improvement in speed of correctly resolved items). Offline reorganization was not enhanced following sleep, but was enhanced following sleep-deprivation in comparison to sleep and daytime wakefulness (solution time of previously incubated, newly solved items). Online performance did not differ between the groups (solution time of new control items).
  
  
  CONCLUSIONS
  The results support the notion that sleep promotes the strengthening, but not the reorganization, of newly encoded memory traces in a verbal creativity task. Future studies are needed to further determine the impact of sleep on different types of memory reorganization, such as associative thinking, creativity and emotional memory processing, and potential clinical translations, such as the augmentation of psychotherapy through sleep interventions.
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: Marion
authors.initials: M
authors.lastname: Kuhn
authors.affiliation: Department of Psychiatry and Psychotherapy, University Medical Center Freiburg, Germany.
authors.forename: Jonathan-Gabriel
authors.initials: JG
authors.lastname: Maier
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: Kai
authors.initials: K
authors.lastname: Spiegelhalder
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
mesh_terms: D000328:Adult; D003405:Creativity; D005260:Female; D005858:Germany; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology*; D011930:Reaction Time; D012890:Sleep / Q000502:physiology*; D012892:Sleep Deprivation / Q000503:physiopathology / Q000523:psychology; D014705:Verbal Behavior / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology; D055815:Young Adult
keywords: CRA; RAT; consolidation; creativity; learning; memory; reorganization; sleep; sleep deprivation; strengthening