EVIDENCE LIBRARY
Can Hangover Lower a Combined Multitasking Score When Individual Tasks Show No Significant Change?
A 25-person crossover study found a lower combined multitasking score during hangover, without significant component-task differences. Why effort, sleep and zero breath alcohol need separate interpretation.
Yes. In a 25-person crossover study, hangover was associated with a significantly lower combined multitasking score even though none of the four component tasks showed a significant difference on its own. Participants also reported more effort and mental demand. That pattern does not mean that all four component abilities were proven impaired, or that the composite score diagnoses an individual driver’s fitness.
Benson and colleagues’ 2020 experiment addresses a distinct issue in DUI evidence: how to interpret a combined performance measure when its individual components are statistically inconclusive.
Four simultaneous tasks, one combined outcome
Participants attended after a typical drinking night and after an alcohol-free night in a semi-naturalistic crossover design. Visit order was counterbalanced. Researchers did not prescribe or directly observe each person’s previous-night alcohol dose.
For 20 minutes, participants worked on mental arithmetic, a Stroop task, letter search and visual tracking displayed simultaneously on a computer screen. Each task was set to a difficult level. The framework generated individual task scores and an overall score based on speed and accuracy.
The combined score was lower during hangover (reported p = .033; Cohen’s d = 0.46). The paper states that performance on the four individual tasks did not differ significantly between conditions. A positive aggregate result and null component results can coexist because the measures summarize performance differently. This finding does not identify which component contributed most or establish a unique mechanism.
Morning breath testing and previous-night estimates were different evidence
The investigators used a regularly calibrated Lion Alcolmeter SD400PA to ensure a displayed alcohol value of 0.00% before testing. Although the paper calls this BAC, the instrument measured breath. It was not a paired forensic whole-blood ethanol assay.
The mean previous-night estimated BAC of 0.135% was calculated from reported drinking and total-body-water and elimination assumptions. It was not measured from blood taken during the drinking session. Serum/plasma, urine and biomarkers were not interchangeable measures establishing that historical concentration.
A zero breath display at the morning visit therefore cannot verify the estimated prior peak. Conversely, an estimated prior peak cannot be presented as the alcohol concentration during the cognitive task.
Greater perceived workload did not establish greater stress reactivity
Participants rated the hangover session as more mentally demanding (p = .039), effortful (p = .031) and frustrating (p = .033), and rated their performance as worse (p = .011). They also reported lower alertness and contentment, with greater anxiety and mental fatigue.
However, the multitasking challenge did not produce a demonstrably different mood response specifically because participants had a hangover. The hypothesized additional psychological stress reactivity was not supported. Greater perceived effort and a larger stress response are separate propositions.
No cortisol measurement established a physiological stress effect. It would also exceed the evidence to claim that subjective effort proves a person exhausted every possible compensation strategy while driving.
Sleep and reporting limitations matter
Participants reported poorer sleep quality and more awakenings before the hangover visit. Time to fall asleep and the length of awakenings did not differ significantly. Sleep was assessed by diary, without objective actigraphy. The design cannot separate effects of alcohol-related symptoms from all effects of disrupted sleep and the previous night’s activities.
The final sample was small, young and predominantly female. The paper reports 36 enrolled and 25 analyzed, but its description of seven incomplete participants and one control-visit drinking exclusion does not fully reconcile those totals. That unresolved accounting discrepancy should limit confidence in the recruitment description rather than be silently corrected.
Self-reported drinking creates additional uncertainty, particularly when estimating exposure after a substantial drinking episode. A crossover comparison helps control stable personal differences but does not remove changing sleep, food, activity or expectation effects between visits.
What the finding adds to DUI interpretation
Driving requires coordination of multiple abilities, making combined task performance a relevant research question. But this experiment measured computer multitasking, not on-road driving, lane keeping or crash risk. It did not validate an impairment cutoff or establish sensitivity and specificity for individual drivers.
The result concerns a different endpoint from remembering intended future actions during hangover or alcohol’s differing effects across cognitive domains. Those distinctions matter: neither a single normal-looking subtask nor one positive composite score resolves every functional question.
For an individual case, identify the observed behavior, actual specimen, instrument and timing, together with plausible competing explanations. This study supports careful evaluation of complex performance after drinking; it cannot reconstruct BAC or independently establish a DUI violation.
Primary source
Benson S, Ayre E, Garrisson H, Wetherell MA, Verster JC, Scholey A. Alcohol Hangover and Multitasking: Effects on Mood, Cognitive Performance, Stress Reactivity, and Perceived Effort. Journal of Clinical Medicine. 2020;9:1154. https://doi.org/10.3390/jcm9041154.