The study, published in Nature Neuroscience, found participants allowed a 90-minute nap between learning the first task and the second task, did not show much improvement in the evening, but did show a marked performance improvement on the following morning.
The researchers found sleep helped overcome interference -- the brain processing new information that interferes with remembering old information learned earlier in the day. Another group of participants in the study taught the same skills, but without the nap showed no improvement in their ability to perform the task.
"This part of the study demonstrated, for the first time, that daytime sleep can shorten the time 'how to' memory becomes immune to interference and forgetting," study co-author Avi Karni of the University of Haifa said in a statement. "Instead of 6 to 8 hours, the brain consolidated the memory during the 90 minute nap."