title: Systematic interindividual differences in neurobehavioral impairment from sleep loss: evidence of trait-like differential vulnerability.
abstract: OBJECTIVE
  To investigate interindividual differences in neurobehavioral deficits during sleep deprivation, and to establish to what extent the neurobehavioral responses to sleep loss are a function of sleep history versus trait-like differential vulnerability.
  
  
  METHODS
  Individuals were exposed to sleep deprivation on 3 separate occasions in order to determine the stability of interindividual differences in neurobehavioral impairment.
  
  
  METHODS
  The sleep-deprivation experiments were conducted under standardized laboratory conditions with continuous monitoring of wakefulness. Each subject underwent a laboratory-adaptation session before entering the sleep-deprivation phase of the study.
  
  
  METHODS
  A total of 21 healthy adults (aged 21-38 years) completed the experiment.
  
  
  METHODS
  Subjects came to the laboratory 3 times at intervals of at least 2 weeks. During each laboratory session, they underwent neurobehavioral testing every 2 hours during 36 hours of total sleep deprivation, which was preceded by baseline sleep and followed by recovery sleep. In the week prior to each sleep-deprivation session and on the baseline night in the laboratory, subjects were required to either restrict their sleep to 6 hours per day (prior sleep restriction condition) or to extend their time in bed to 12 hours per day (prior sleep extension condition), so as to experimentally manipulate sleep history (in randomized counterbalanced order).
  
  
  RESULTS
  There was strong evidence that interindividual differences in neurobehavioral deficits during sleep deprivation were systematic and trait-like. The magnitude of interindividual variability was substantial relative to the magnitude of the effect of prior sleep restriction (which on average involved a reduction of 4.1 hours sleep per day, compared to prior sleep extension, for 7 days). Overall, interindividual differences were not explained by subjects' baseline functioning or a variety of other potential predictors. Interindividual variability clustered on 3 distinct neurobehavioral dimensions: self-evaluation of sleepiness, fatigue, and mood; cognitive processing capability; and behavioral alertness as measured by sustained attention performance.
  
  
  CONCLUSIONS
  Neurobehavioral deficits from sleep loss varied significantly among individuals and were stable within individuals. Interindividual differences in neurobehavioral responses to sleep deprivation were not merely a consequence of variations in sleep history. Rather, they involved trait-like differential vulnerability to impairment from sleep loss, for which neurobiologic correlates have yet to be discovered.
authors.affiliation: Unit for Experimental Psychiatry, Division of Sleep and Chronobiology, Department of Psychiatry, and Center for Sleep and Respiratory Neurobiology, University of Pennsylvania School of Medicine, Philadelphia 19104-6021, USA. vdongen@mail.med.upenn.edu
authors.forename: Hans P A
authors.initials: HP
authors.lastname: Van Dongen
authors.forename: Maurice D
authors.initials: MD
authors.lastname: Baynard
authors.forename: Greg
authors.initials: G
authors.lastname: Maislin
authors.forename: David F
authors.initials: DF
authors.lastname: Dinges
mesh_terms: D000223:Adaptation, Psychological; D000328:Adult; D001921:Brain / Q000503:physiopathology*; D016000:Cluster Analysis; D003072:Cognition Disorders / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D017286:Polysomnography; D011597:Psychomotor Performance; D012892:Sleep Deprivation / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*; D011795:Surveys and Questionnaires; D014851:Wakefulness / Q000502:physiology