Effects of a moderate evening alcohol dose. II: performance.
BACKGROUND
This second of a pair of papers investigates the effects of a moderate dose of alcohol and staying up late on driving simulation performance and simple visual reaction time (RT) at a known circadian phase in well-rested young adults.


METHODS
Twenty-nine adults (9 males), ages 21 to 25 years, spent 1 week on an at-home stabilization schedule of 8.5 to 9 hours, followed by 3 nonconsecutive nights in-lab: adaptation, placebo, and alcohol. Performance task practice occurred on 3 occasions before the study. Alcohol (vodka; 0.54 g/kg men; 0.49 g/kg women mixed with tonic) was consumed over 30 minutes ending 1 hour before normal bedtime; the same quantity of beverage was given on placebo. Driving simulation (with drive-only and dual-task drive and subtract components) and psychomotor vigilance task (PVT) testing occurred before and after alcohol/placebo ingestion. Breath alcohol concentration (BrAC) readings were taken before all test sessions. Saliva samples were taken approximately every 30 minutes to determine circadian phase.


RESULTS
Driving simulation and PVT variables significantly deteriorated with increasing time awake. Driving simulator lane variability was worse with alcohol compared with placebo at 15.5 hours awake. No PVT variable showed an effect of alcohol.


CONCLUSIONS
Driving simulation performance deteriorated with extended waking and with alcohol; driving was most impaired at the peak alcohol level. The PVT, less complex than the driving simulation, did not show effects of alcohol, a finding consistent with previous literature that disruptive effects of low alcohol concentrations increase with task complexity. Overall, simulated driving performance is significantly impaired late at night when even a moderate dose of alcohol is consumed.
Rupp
Tracy L
TL
E.P. Bradley Sleep and Chronobiology Laboratory, Providence, Rhode Island, USA. tracy.rupp@amedd.army.mil
Acebo
Christine
C
Seifer
Ronald
R
Carskadon
Mary A
MA
D000328:Adult; D001143:Arousal / Q000187:drug effects; D001334:Automobile Driving; D001944:Breath Tests; D002492:Central Nervous System Depressants / Q000493:pharmacokinetics / Q000494:pharmacology*; D002940:Circadian Rhythm / Q000187:drug effects; D000431:Ethanol / Q000493:pharmacokinetics / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008297:Male; D008550:Melatonin / Q000378:metabolism; D011597:Psychomotor Performance / Q000187:drug effects*; D011930:Reaction Time / Q000187:drug effects; D012463:Saliva / Q000378:metabolism
D002492:Central Nervous System Depressants; D000431:Ethanol; D008550:Melatonin