Re: Why do we come up with solutions to difficult problems during sleep?

     The ability to come up with solutions during sleep is not unusual, 
although it is probably not universal either. Throughout the centuries 
there have been countless examples of important discoveries being made 
either while asleep or important clues being suggested while in an 
“unconscious” state. Perhaps the most famous example is that of Friedrich 
August von Kekule, who “discovered” the structure of benzene while 
sleeping. According to Kekule, “one of the snakes had seized hold of its 
own tail, and the form whirled mockingly before my eyes. As if by a flash 
of lightning I awoke”.   The poet Samuel Taylor Coleridge also reports 
composing his famous poem “Kubla Khan” essentially while sleeping. 
    Why does this occur?   One possible explanation is the effect of 
incubation.  There are several ways that this may work. One is that simply 
stepping away from a problem, such as engaging in another activity will 
help the person come up with a solution (for example, taking a walk, 
listening to music, etc.).  Another possibility is that incubation allows 
our “unconscious” to take over and solve the problem for us.  The famous 
psychoanalyst Sigmund Freud suggested that dreams are the “Royal Roads” to 
the unconscious. In this case, sleeping allows us to tap into this 
resource.  Another explanation is that we tend to solve problems better 
when we are in a relaxed state and sleeping of course helps produce this 
condition.  A somewhat related explanation is that dreaming helps us 
visualize our problems and solutions more efficiently and this then makes 
solutions more salient.  
     I should however offer a word of caution here. Much of the evidence in 
support of the role of sleep, dreams or the unconscious in problem solving 
or creativity largely involves case studies. Objective scientists generally 
have problems with this type of evidence because it is often unreliable or 
nonreplicable. For example, there is little objective experimental evidence 
in support of either incubation effects or the role of the unconscious in 
problem solving. This is not to say that we should totally discount these 
forces, but we should be careful about accepting any broad generalizations 
about their effects or their importance.  Unfortunately problem solving and 
creativity are topic areas that we just do not totally understand at this 
point.  Some of the books that discuss these issues in detail are: The 
nature of creativity, by Robert Sternberg; and Creativity: Beyond the myth 
of genius, by Robert W. Weisberg.  The WWW is of course another source of 
information.