Under the Microscope: Many people have had the following experience. You grapple mentally with a difficult problem all evening but make little or no progress at solving it.
You go to sleep and on awakening eight hours later the solution to the problem pops effortlessly into your head. Although such anecdotal evidence is common only recently has experimental evidence come to light that sleep benefits insight (Wagner and collaborators, Nature Vol. 427, pp 352-355, 2004).
Wagner and his collaborators tested subjects as follows. The participants were asked to transform strings of eight digits into new strings of seven digits applying two simple rules sequentially from one digit to the next. The last digit in the transformed string is the final solution. Unknown to the participants is a rule hidden in the material: the last three responses mirror the three preceding ones, for example 1, 9, 1, 4, 4, 1, 9. Discovering this hidden rule greatly speeds up the solution of the task as the final solution (in this case 9) is known when the second digit is specified.
Participants were trained in the task by running through it three times and eight hours later were tested 10 times. During the eight-hour period the subjects were either kept awake or they slept.
When they were tested, the percentage who gained insight into the hidden rule was 60 per cent in those who had slept and only 22 per cent in those who had remained awake. In other words, sleep aids insight when a memory has been formed before the sleep period.
Numerous famous creative insights, scientific and artistic, have been attributed to dreams. Many of these are recounted in an article by Josephine Ross in The Psychologist, December 2006.
Elias Howe (1819-1867) patented the first sewing machine. He had a dream in which he was pursued by cannibals, each wielding a spear with a hole at the tip. He realised that the way to make his sewing machine work was to move the thread hole from the base to the tip of the needle.
August Kekulé (1829-1896) discovered the ring structure of benzene in a dream in which a string of carbon atoms danced around like a snake. One of the "snakes" got hold of its tail and twisted about in a circle. When Kekulé awoke he quickly realised that the benzene molecule has a ring structure.
Dimitri Mendeleyev (1834-1907) formulated the periodic table of the elements on which modern chemistry is based. It is said that the insight behind the table came to him in a dream in which he saw that the basic chemical elements are related to each other like themes and phrases in music.
Einstein (1875-1955) paid a lot of attention to his dreams and credited insight into his theory of relativity to a dream of sledging down a mountain and noting how the appearance of stars changed relative to his speed.
Also, the Danish physicist Neils Bohr (1885-1962) credited a dream of a horse racing around a race track with providing insight into how electrons orbiting the atomic nucleus are restricted to discrete energy levels.
Otto Loewi (1893-1961) shared the 1936 Nobel Prize in Physiology or Medicine for discovering the chemical nature of nerve signal transmission from one cell to another. He dreamed the solution to the problem one night, woke up and made a note on a piece of paper. Next morning he couldn't read his scribble. The next night he had the dream again and woke up. This time he got up and went to the laboratory where he experimentally confirmed his dreamed solution.
Samuel Taylor Coleridge (1772-1834) claimed that his great poem Kubla Khan came to him word for word in an opium-induced dream. The opening lines are:
In Xanadu did Kubla Khan
A stately pleasure-dome decree:
Where Alph, the sacred river, ran
Through caverns meaningless
to man
Down to a sunless sea.
Robert Louis Stevenson (1850-1894) credited the plot of Dr Jekyll and Mr Hyde to a dream, and Salvador Dali described paintings in his Surreallism period as "hand-painted dream photographs".
Poet laureate Ted Hughes (1930-1998) claims he dreamed the full text of his play The Wound, and the horror writer Stephen King (1947-) dreamed the plot for his 1988 novel Misery.
Beatle, Paul McCartney (1942-) composed Yesterday following a dream and subsequently had to be convinced that the melody was his own creation. Parts of Handel's Messiah and Wagner's Tristan and Isolde are said to have come from dreams. Mozart, Beethoven and Schubert also referred to music derived from their dreams.
At the age of 21, the composer Guiseppe Tartini dreamed he sold his soul to the devil for a composition. The devil grabbed his violin and played "the most exquisite, enchanting and breathtaking sonata". Tartini composed The Devil's Trill on awakening and declared, although it was the best he ever wrote, it was far inferior to what he heard in his dream.
Although there is no scientific consensus as to the exact value of sleeping and dreaming, I think we can safely assume that the third of our lives we spend asleep has evolved to perform useful, probably essential, functions.
And finally there was the chap who dreamed about having an argument. He demolished his adversary with the most brilliant ever put-down line. He awoke in his excitement and jotted down the brilliant riposte on a piece of paper. Next morning he couldn't remember the line so he eagerly consulted the piece of paper. It read: "And the same to you!"
William Reville is associate professor of biochemistry and public awareness of science officer at UCC - http://understandingscience.ucc.ie.