This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Our study proposes to increase understanding of the residual effects of heavy drinking by addressing several questions. We will test several hypotheses regarding the mechanism by which heavy drinking effects next-day performance. Using a placebo-controlled randomized trial, we will dose participants with placebo or with a high or low congener alcoholic beverage (to a level of 0.10 g% BAC) the night before testing their neurobehavioral performance as measured by validated tests of cognitive impairment using the computer based Neurobehavioral Evaluation System (NES 3). In addition, we will test participant impairment due to fatigue using computer based Psychomotor Vigilence Testing (PVT). We will monitor participants' sleep to assess sleep disturbance; collect information on hangover symptoms the morning after dosing; and collect data on participants' family history of drinking problems. We will test the following hypotheses: (1) relative to placebo, heavy drinking will degrade next-day cognitive functioning as measured by the NES3 (2) relative to placebo, heavy drinking will degrade next-day reaction time as measured by the PVT; and both the NES3 and the PVT will be mediated in full or in part by quality of sleep; (3) a high congener alcoholic beverage will affect performance to a greater degree than a low congener beverage and this relationship will be mediated by severity of hangover symptoms; and (4) the residual effects of heavy drinking on next-day performance will be attenuated among participants positive for a family history of alcohol problems, relative to family-history-negative participants. The study procedure will be conducted twice with one week in between, switching the individuals' dosing status.