Sleep On It

A fascinating study in Nature magazine* shows that sleep can increase the chance you’ll have a creative insight.

Many of us have had the experience of waking up with a great idea, or having an insight while in the shower right after waking up.  And many famous creators have said that they got their ideas while dreaming or sleeping.  But there hasn’t been any scientific, experimental evidence of the power of sleep–until now.

A team of German researchers posed the “Number Reduction Task” (NRT) to 66 people.  In the NRT, you’re given a list of 8 digits, and the list contains only the digits 1, 4, and 9. You’re also given the first digit of the new list of 8 digits that you’ll generate below the first:

1  1  4  4  9  4  9  4


Your task is to find the eighth digit.  To do this, you start by generating another 7 digits, underneath the first list, by applying the following rules from left to right:

To generate the next digit, compare the new digit to the left with the old digit above and to the right.  Apply one of these two rules: if those two digits are the same, then write down that same digit; if they are different, then write down the third digit (that’s different from both of them).  You’d be comparing 1 with 1, so you’d get 1 again:

1  1  4  4  9  4  9  4

1   1

But the third time, you’re comparing 1 with 4 so the third new digit is 9.  To get the fourth new digit, you’d be comparing 9 with 4, so the fifth new digit is 1, etc.  But remember: your only assignment is to find the 8th and final new digit.  (Go ahead, try it!)  This took their subjects about 9 seconds each time.

All 66 subjects worked through 90 of the above NRTs.  Then one group of 22 people got 8 hours of sleep, and a second group of 22 people stayed awake overnight.  A third group of 22 did the first 90 in the morning and then stayed awake during the day.  Then all 66 worked through 300 NRTs.

What the subjects didn’t know is that all of these number strings were created in such a way that the last three new digits mirrored the previous three.  (As you’ll see if you completed the above NRT.)  So once you discover that rule, you know that the third digit in the list–the second one that you write–is going to also be the final digit.  Once subjects discovered this rule, the time it took them to solve an NRT dropped from 9 seconds to less than 3 seconds.

So: did sleep help?  Absolutely!  Of the 44 people that stayed awake for 8 hours (overnight or during the day) 22.7 percent of them discovered the rule during the retesting.  But of the 22 that slept, 59.1 percent discovered the rule–more than twice as many!  (Five people discovered the rule during the first batch of testing and they were dropped from the study.)

Of course, simple number games like this are a far cry from the kinds of innovations that change the world and improve your life.  But this study confirms what many of us have experienced: If you’re working late, stumped by a tough problem, stop working and go to bed.

*Ullrich Wagner, Steffen Gais, Hilde Haider, Rolf Verleger, and Jan Born (2004).  Sleep inspires insight. Nature Vol. 427 January 2004 pp. 352-355.