Those who take a nap and dream about a task they've just learned, perform it better upon waking than either those who don't sleep at all or those who sleep but don't report any associated dreams.

The learners in the study were asked to sit in front of a computer screen and learn the layout of a three-dimensional maze so that they could find their way to a landmark (a tree) when they were put down at a random location within the virtual space five hours later.

It was found that those who were allowed to take a nap and also remembered dreaming of the task found the tree in less time. In a couple of cases, the dreamers said they recalled just the music from the computer maze. One participant said they were dreaming that there were people at particular checkpoints in the maze, even though the real maze didn't have any people or checkpoints. Another said they dreamt about an experience they'd had tromping through bat caves and thinking that the caves were like mazes.

It was concluded that it's not that the dreams led to better memory, but rather that they are a sign that other, unconscious parts of the brain were working hard to remember how to get through the virtual maze.