This study examined whether three sleep‐related variables (current sleepiness, the duration of the previous night's sleep and the quality of that sleep) were predictors of an eyewitness's ability to remember central and peripheral details from a crime. Participants first completed a self‐report questionnaire assessing their current sleepiness, then watched a video of a bank robbery, next completed a self‐report questionnaire about their previous night's sleep, and then had their memory of the crime tested. It was found that as the eyewitnesses' sleep quality decreased and their sleepiness increased, their ability to accurately recollect peripheral details from the crime was compromised. This is the first demonstration that variations in sleep prior to witnessing a crime, and sleepiness at the time of a crime, can predict eyewitness memory. Copyright © 2013 John Wiley & Sons, Ltd.