to be well rested than well read. (Of course, it’s actually better to be both!)

How are we sure that we’re really learning while we sleep? Probably you’ve witnessed it for yourself, though you may not have realized it at the time. Think back to a time when you had to make a big decision—say, whether you were ready to leave a job you really liked but were no longer challenged by. You likely gathered lots of information— what the job market was like, the names of people you could contact who might know of available positions, how comfortable you would feel changing companies or even your career at this point in your life— but you just couldn’t come to grips with the question. To try to stop obsessing, you reviewed statistics and names and assessed your inner feelings and then gave yourself a deadline of the following day. Wisely, you slept on your decision—and were amazed to discover when you woke up that you knew exactly the right thing to do.

You can also see proof that you learn during the night by taking a simple finger-tapping test, the point being to see how many times you can tap your finger, or four fingers in sequence, in a certain amount of time. For example, try tapping four fingers in sequence, from pinky to index finger, at 10:00 in the morning for 30 seconds; write down how many times you complete the sequence. Then try the same thing again at 10:00 at night—the number of completions should be about the same. But then repeat the exercise the following morning—and be surprised. You’ll probably see an improvement in speed of up to 26 percent—a huge gain. Studies have shown that people taking this test continue to improve over a three-night period in both speed and accuracy—without practicing at all in between.