MedicalResearch.com Interview with: Marc Züst, PhD University of Bern Department of Psychology Division of Experimental Psychology and Neuropsychology Switzerland  MedicalResearch.com: What is the background for this study? What are the main findings? Response: Slow wave sleep (deep sleep) is known to be very important for memory reorganization. The brain goes through the memory traces that were created during wakefulness and strengthens the important ones, while unimportant ones are weakened or deleted to make room for new learning the next day. This happens during the peaks of the eponymous slow waves, also called up-states, where the brain is highly active and interconnected. Up-states last for about 0.5 sec before transitioning into down-states, where the brain is relatively silent. Based on these findings, we hypothesized that up-states constitute windows of opportunity to learn new information during slow wave sleep: The "channels are open", and the brain is already performing memory functions. The results of our study support this hypothesis. We found that, if we repeatedly managed to synchronize presentation of word pairs with up-states, memory for these pairs was best. Moreover, we find a dose-response function: The more often word pairs hit up-states, the better the memory. On top of that, fMRI during the retrieval test suggests that the same brain regions are involved in sleep learning as are involved in learning during wakefulness. (more…)