Per Davidson

This proposal will examine if a daytime nap improves memory consolidation, with the largest and most diverse sample size of any study ever conducted on this topic. We will achieve this through a preregistered multi-lab collaboration with contributing sleep labs from all over the world. Previous research has indicated that sleep is beneficial for memory consolidation

it has further been suggested that sleep mainly consolidates emotional memories, and that sleep helps to reduce the emotional reactivity associated with emotional experiences. Recent meta-analytic work has, however, revealed that previous studies on this topic have been massively underpowered and that selective publishing of positive findings is a major problem in the field. The study will have a within-subject crossover design. Participants will come to the lab in the early afternoon and encode neutral and negative images. For each image, they will also rate the emotional response it elicits. Participants will then either take a nap, monitored with polysomnography, or spend an equivalent amount of time awake, and then have their memory performance for the images tested, and rate their emotional response to the images once again. This research design will allow us to answer the following questions: A) will sleep, as compared to wake, increase memory consolidation? B) Will this sleep dependent-consolidation benefit be more pronounced for negative compared to neutral items? C) Will any particular sleep stage be especially involved in memory consolidation? D) Will sleep, as compared to wake, decrease the emotional reaction to previously viewed images? By doing this as a registered report, we will increase transparency and reduce risk of selective reporting of significant results. This study will, for the first time, produce robust and reliable estimates that will inform us about the putative benefits of promoting sleep in the immediate aftermath of learning experiences and/or negative events.