Quantifying the performance impairment associated with fatigue

Abstract

SUMMARYThe present study systematically compared the effects of fatigue and alcohol intoxication on a range of neurobehavioural tasks. By doing so, it was possible to quantify the performance impairment associated with fatigue and express it as a blood alcohol impairment equivalent. Twenty-two healthy subjects aged 19-26 years participated in three counterbalanced conditions. In the sustained wakefulness condition, subjects were kept awake for 28 h. In the alcohol and placebo conditions, subjects consumed either an alcoholic or non-alcoholic beverage at 30 min intervals, until their blood alcohol concentration reached 0.10%. In each session, performance was measured at hourly intervals using four tasks from a standardised computerbased test battery. Analysis indicated that the placebo beverage did not significantly effect mean relative performance. In contrast, as blood alcohol concentration increased performance on all the tasks, except for one, significantly decreased. Similarly, as hours of wakefulness increased performance levels for four of the six parameters significantly decreased. More importantly, equating the performance impairment in the two conditions indicated that, depending on the task measured, approximately 20-25 h of wakefulness produced performance decrements equivalent to those observed at a blood alcohol concentration (BAC) of 0.10%. Overall, these results suggest that moderate levels of fatigue produce performance equivalent to or greater than those observed at levels of alcohol intoxication deemed unacceptable when driving, working and/or operating dangerous equipment.

Consequences of sleep deprivation

“…Prolonged microepisodes of sleep during driving considerably reduce the driving safety [59]. With regard to such parameters as the concentration of attention, reflexes, perceptiveness and accuracy of task performance, the effects of a 24-hour sleep deprivation, or of a 4-5-hour night sleep repeated over a period of one week, are similar to those induced by the 0.5-1‰ level of blood alcohol concentration [153][154][155][156][157]. In most of the European countries, the highest permissible blood level of alcohol in car drivers is 0.5‰, and the Polish law permits only the values below 0.2‰.…”

The driver vigilance telemetric control system (DVTCS): Investigating sensitivity to experimentally induced sleep loss and fatigue

“…The experimental protocol was specifically chosen to produce measurable and meaningful levels of impairment in participants (as based on Lamond & Dawson, 1999). Furthermore, this protocol was also run using dim light and no social interaction.…”

“…The protocol reflected that used by Lamond and Dawson (1999), mentioned above, in order to ensure that the participants reached levels of fatigue that were measurable and meaningful. That is, after remaining awake for a single night (20-24 consecutive hours), participants in this study demonstrated levels of performance impairment that were equivalent to someone with a BAC twice the legal driving limit in Australia (0.10% BAC).…”

Performance and Psychophysiological Measures of Fatigue Effects on Aviation Related Tasks of Varying Difficulty

“…In fact, it now appears that overly-tired aviators may face operational risks similar to those posed by alcohol intoxication. Recent studies have established that from 17-25 hours of sustained wakefulness can produce an array of performance deficits equivalent to those observed with blood alcohol concentrations (BAC's) of 0.05% to 0.10%--the legal limits for driver intoxication (Dawson and Reid, 1997;Lamond and Dawson, 1999).…”