‘Sleeping on a problem’ may be the best way to solve it

A research has suggested that the best way to solve a complicated problem is to distract yourself for a few minutes with something else or sleep on it overnight.

However, as with most summaries of psychological studies I read, the actual experiment described seems somewhat limited, and the conclusion is an extrapolation from specific to general, without clearly showing that other factors have been eliminated. But that may just be a limitation of the reporting.