Sleep is ubiquitous in animals and humans and vital for healthy functioning. Thus, sleep after training improves performance on various tasks in comparison to equal periods of active wakefulness. However, it has been unclear so far whether this is due to an active refinement of neural connections or merely due to the absence of novel input during sleep. Now researchers at the Medical Center—University of Freiburg have succeeded in showing that sleep is more than rest for improving performance. The findings, which were published in the journal Sleep on January 6, 2021, provide important information for planning periods of intensive learning or training.