NOVA | scienceNOW | Sleep: Test Yourself

What constitutes a memory? Many of us may think of a memory as something verbal—a line of haiku poetry we recited in fourth grade—or something visual—a flashback to an angry look or loving smile. But there are other types of memories we may not be conscious of at all, including procedural memories involved in learning and mastering motor skills like swinging a tennis racket. When you learn the proper upward follow-through, for instance, this know-how (which some term "muscle memory") is encoded in your neurons. And research suggests that sleep enhances such memories, that you can become a better tennis player or musician or whatever not just by practicing but also by "sleeping on" skills you've recently acquired.—Susan K. Lewis

To see this intriguing phenomenon in action, try this simple test* overnight:

In the evening, open a word-processing document.
Tap out five numbers (e.g., "41324") in a large font at the top of the page. This will be your reference; you can look at the sequence as you do the next step.
Below the number, and using your non-preferred (non-dominant) hand, start typing the sequence as fast as you can for 30 seconds, each sequence on a new line. Don't correct mistakes; just keep typing. At the end of 30 seconds of typing, you have completed one trial. Repeat the typing task for eight trials altogether, resting for 30 seconds between trials.
To quickly count how many correct sequences you tapped out in each trial, use your word-processing program's "find and replace" feature (e.g., find "41324" and replace with "X"). Then just count the number of X's per trial.
The next morning, repeat the exercise, using the same five-number sequence and same hand.
Now, compare your performance on the last few trials of day 1 (trials 6-8) to the first few trials of day 2 (trials 9-11).

How did you do? Let us know on the NOVA scienceNOW discussion board.

* Many thanks to Matt Walker of Harvard Medical School for suggesting this test, adapted from research he and colleagues did for the 2002 study "Practice With Sleep Makes Perfect: Sleep Dependent Motor Skill Learning." Neuron 35:205-211.