Quantifying the performance impairment associated with fatigue

The present study systematically compared the effects of fatigue and alcoho l intoxication on a range of neurobehavioural tasks. By doing so, it was po ssible to quantify the performance impairment associated with fatigue and e xpress it as a blood alcohol impairment equivalent. Twenty-two healthy subj ects 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 o r non-alcoholic beverage at 30 min intervals, until their blood alcohol con centration reached 0.10%. In each session, performance was measured at hour ly intervals using four tasks from a standardised computer-based test batte ry. Analysis indicated that the placebo beverage did not significantly effe ct mean relative performance. In contrast, as blood alcohol concentration i ncreased performance on all the tasks, except for one, significantly decrea sed. Similarly, as hours of wakefulness increased performance levels for fo ur of the six parameters significantly decreased. More importantly, equatin g the performance impairment in the two conditions indicated that, dependin g on the task measured, approximately 20-25 h of wakefulness produced perfo rmance decrements equivalent to those observed at a blood alcohol concentra tion (BAC) of 0.10%. Overall, these results suggest that moderate levels of fatigue produce performance equivalent to or greater than those observed a t levels of alcohol intoxication deemed unacceptable when driving, working and/or operating dangerous equipment.