They found that when the brain kicks back into gear, the conscious thought process picks up on the solution.
The 'god sent' discovery was made after a team of scientists asked 130 volunteers to conduct a word association experiment.
Half the group were told to break off from their test to concentrate on something entirely different for five minutes.
The results showed that those who spent time focusing on a different task were much quicker at solving the first task when they returned to it than the group that had stuck with it.
The research has been led by a team at Northwestern University in Illinois.
"Conscious thought is better at making linear, analytic decisions, but unconscious thought is especially effective at solving complex problems. Unconscious activation may provide inspirational sparks underlying the 'Aha!' moment that eventually leads to important discoveries," the Telegraph quoted Professor Adam Galinsky, who led the study, as saying.
The study has been published in the September issue of the journal Psychological Science.