Individual vulnerability of cognitive performance impairment after alcohol consumption predicts vulnerability to sleep loss

Abstract

Objectives The vulnerability of cognitive performance to sleep loss varies largely among individuals. It has been proposed that these interindividual differences are related to the effects of adenosine in the brain which is known to increase sleepiness and sleep propensity. The performance impairing effects of alcohol have been suggested to be mediated in part by the inhibitory actions of cerebral adenosine. In the rat brain it has been reported that ethanol increases extracellular adenosine. Therefore, we investigated whether vulnerability to sleep loss can be predicted by the vulnerability of performance after alcohol intake. Methods and materials Individual susceptibilities to sleep loss and alcohol consumption were examined in 47 volunteers (mean age 27 ± 5 (SD) years, 21 female). Performance was tested using a 10-min Psychomotor Vigilance Task (PVT) every 3 hours during wake time. Participants were exposed once to 38 hours of total sleep deprivation and once to acute alcohol administration aimed at yielding a blood alcohol concentration (BAC) of 0.08%. After alcohol intake at 4 pm 35 participants had reached a BAC of more than 0.06% immediately prior to the PVT session at 6 pm (mean BAC 0.074%, SD 0.009%, min. 0.063%, max. 0.095%). Two nights of recovery were scheduled between conditions. Baseline performance was recorded at the beginning of the investigation following an 8-hour sleep period. Results from the 6 pm PVT sessions are reported. Results PVT performance impairments after 35 hours of sustained wakefulness and after acute alcohol intake, assessed both as deviations from baseline performance, correlated highly (i.e. 10% slowest reaction times: Pearson’s r=0.73, p<0.0001; standard deviation of reaction times: r=0.75, p<0.0001; response speed: r=0.47, p=0.0043). Conclusions Individuals who showed good performance under sleep deprivation proved more resistant to the effects of alcohol consumption while persons who suffered strong performance impairments due to sleep loss did likewise after alcohol intake. This pattern suggests that sleep deprivation and alcohol effects on performance may share – at least in part – common pathways, possibly involving the adenosinergic system.