Sleep aids the consolidation of recently acquired memories. Evidence strongly indicates that sleep yields substantial improvements on recognition memory tasks relative to an equivalent period of wake. Despite the known benefits that sleep has on memory, researchers have not yet investigated the impact of sleep on eyewitness identifications. Eyewitnesses to crimes are often presented with a lineup (which is a type of recognition memory test) that contains the suspect (who is innocent or guilty) and fillers (who are known to be innocent). Sleep may enhance the ability to identify the guilty suspect and not identify the innocent suspect (i.e., discriminability). Sleep may also impact reliability (i.e. the likelihood that the identified suspect is guilty). In the current study, we manipulate the presence or absence of sleep in a forensically relevant memory task. Participants witness a video of a mock crime, make an identification, or reject the lineup, and rate their confidence. Critically, some participants sleep between witnessing the crime and making a lineup decision, while others remain awake. Based on prior memory research we predict that those in the sleep condition will have greater discriminability compared to those who had equivalent periods of wake. Sleep’s role in shaping reliability is completely unknown and our work will be the first to explore this variable. This work will be of significant theoretical and applied importance.