title: Socializing by Day May Affect Performance by Night: Vulnerability to Sleep Deprivation is Differentially Mediated by Social Exposure in Extraverts vs Introverts.
abstract: OBJECTIVE
  to examine the effects of socially enriched versus socially impoverished environments on performance and alertness decline during sleep deprivation in extraverts versus introverts.
  
  
  METHODS
  participants (n = 29 men, n = 19 women) were assigned to socially enriched (n = 24; 13 introverts, 11 extraverts) or socially impoverished (n = 24; 12 introverts, 12 extraverts) conditions (activities matched) for 12 hours (1000-2200) on Day 1 followed by 22 hours of sleep deprivation (2200-2000; 36 h awake total), monitored by actigraphy. The median split of volunteers' Eysenck Extraversion scores was used for extravert/introvert categorization. The Psychomotor Vigilance Task (PVT), modified Maintenance of Wakefulness Test (MWT), and Stanford Sleepiness Scale (SSS) were administered every 2 hours throughout. PVT speed, transformed lapses, modified MWT sleep-onset latency, and SSS were analyzed using mixed-model analyses of variance, with covariates of age and total actigraphic activity during enrichment or impoverishment.
  
  
  METHODS
  residential sleep/performance testing facility.
  
  
  METHODS
  forty-eight healthy adults (aged 18-39).
  
  
  METHODS
  Twelve hours of socially enriched or isolated environments in extraverts and introverts prior to sleep deprivation.
  
  
  RESULTS
  Social experience interacted with personality type to affect alertness and vigilance. Social enrichment, as compared with social impoverishment, was associated with more PVT lapses at 04:00 overall. Similarly, following social enrichment, PVT speed was significantly slower among extraverts than among introverts during sleep deprivation, but no personality-group differences emerged following social impoverishment. MWT sleep latency and SSS subjective sleepiness did not show significant personality or social-condition effects during sleep deprivation.
  
  
  CONCLUSIONS
  the effect of social exposure on vulnerability or resiliency to sleep deprivation was modulated by introversion and extraversion. Extraverts exposed to social environments were more vulnerable to subsequent sleep deprivation than were introverts.
authors.affiliation: Behavioral Biology Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, USA. tracy.rupp@amedd.army.mil
authors.forename: Tracy L
authors.initials: TL
authors.lastname: Rupp
authors.forename: William D S
authors.initials: WD
authors.lastname: Killgore
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Balkin
mesh_terms: D056044:Actigraphy / Q000379:methods; D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000704:Analysis of Variance; D002940:Circadian Rhythm; D005120:Extraversion, Psychological; D005260:Female; D006801:Humans; D007439:Introversion, Psychological; D008297:Male; D010551:Personality; D017286:Polysomnography / Q000379:methods; D011597:Psychomotor Performance; D012016:Reference Values; D012892:Sleep Deprivation / Q000503:physiopathology / Q000523:psychology*; D012919:Social Behavior; D012931:Social Environment; D014851:Wakefulness; D055815:Young Adult