Perception of simulated driving performance after sleep restriction and caffeine

Sarah N. Biggs*, Andrew Smith, Jill Dorrian, Kathryn Reid, Drew Dawson, Cameron van den Heuvel, Stuart Baulk

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

62 Scopus citations


Objective: As feelings of alertness are reported to be highly correlated with performance perception, the objective of this study was to determine whether caffeine, a common countermeasure to driver sleepiness, affected a sleepy driver's ability to monitor his or her simulated driving performance. Methods: Twelve healthy young adults (six males, six females) participated in three counterbalanced, blinded, daytime conditions: control [9 h time in bed (TIB)], 100 mg caffeine (4 h TIB), and placebo (4 h TIB). Driving performance was measured through lane drift on a series of 30-min simulated driving sessions. Subjective sleepiness and perception of driving performance were measured at 5-min intervals during driving sessions via the Karolinska Sleepiness Scale and a corresponding perception scale. Results: Sleep restriction had a significant detrimental effect on driving performance and subjective measures. Caffeine resulted in significant improvements across all measures. Subjective measures were found to be significantly correlated after sleep restriction and prior to caffeine. Correlations between actual and perceived performance were nonsignificant across all conditions. Conclusions: The strong correlation between subjective measures supports the postulation that sleepiness is used as a cue for performance prediction when sleep restricted. The relationship between perceived and actual performance after fatigue countermeasures remains inconclusive. Further research, addressing limitations, is needed.

Original languageEnglish (US)
Pages (from-to)573-577
Number of pages5
JournalJournal of Psychosomatic Research
Issue number6
StatePublished - Dec 2007


  • Caffeine
  • Driver sleepiness
  • Perception
  • Simulated driving
  • Young drivers

ASJC Scopus subject areas

  • Psychiatry and Mental health
  • Clinical Psychology


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