While we sleep, our subconscious minds continue to work on problems our conscious minds have failed to solve.
Most people who have struggled with a crossword clue know that sometimes they have found the answer easily after sleeping on the problem.
‘Sleeping on it’ has also led to major scientific discoveries, such as the seven examples below.
Discovery of the Periodic TableDmitri Mendeleev was obsessed with finding a logical way to organize the chemical elements. It had been preying on his mind for months.
In 1869 he wrote the elements’ names on cards – one element on each card. He then wrote the properties of every element on its own card.
He saw that atomic weight was important in some way, but he could not find a pattern.
Convinced that he was close to discovering something significant, Mendeleev moved the cards about for many hours until finally he fell asleep at his desk.
When he awoke, he found that his subconscious mind had done his work for him! A logical arrangement of the elements had come to him. He later wrote:
More about Dmitri Mendeleev
Discovery of Evolution by Natural Selection
Alfred Russel Wallace had traveled in Brazil and South East Asia recording the species he found, trying to understand the differences he saw when species were separated by geographical barriers.
For years he had been considering the problem of how new species could arise, but could not find the answer.
In 1858 had an extreme dream, in the shape of hallucinations caused by a tropical fever. When the fever had gone, he found that the theory of evolution by natural selection had come to him.
More about Alfred Russel Wallace
Discovery of the Structure of Benzene and Aromatic Chemistry
August Kekulé had been worrying about how the atoms in benzene arranged themselves.
It was a tough problem, because the ratio of carbon and hydrogen atoms was unlike that seen in other hydrocarbon compounds.
On a cold night in 1865, he had been working on the problem in his room.
Unable to find a solution, he turned his chair to the fire and dozed.
He began dreaming of atoms dancing. Gradually the atoms arranged themselves into the shape of a snake. Then the snake turned around and bit its own tail.
The image of the snake, tail in its mouth, continued to dance before his eyes. When Kekulé awoke, he realized what the dream had been telling him:
Benzene molecules were made up of rings of carbon atoms.
Understanding these aromatic rings opened up an extremely important, completely new field of chemistry and a new understanding of chemical bonding.
Thousands of New Mathematical Ideas
Srinivasa Ramanujan had negligible formal training in mathematics. He died tragically young, aged 32. In his short lifetime he produced almost 4000 proofs, identities, conjectures and equations in pure mathematics.
Although he died in 1920, the richness of his ideas and conjectures in fields such as Elliptic Functions and Number Theory – nearly all of which were correct – were ahead of his time, and continue to inspire and direct the research carried out by mathematicians today.
The Cambridge University mathematician Godfrey H. Hardy, who worked with Ramanujan, expressed the thought that if mathematicians were rated on the basis of pure talent on a scale from 0 to 100, he himself would be worthy of 25, J.E. Littlewood 30, David Hilbert 80, and Srinivasa Ramanujan 100.
Ramanujan said that the Hindu goddess Namagiri would appear in his dreams, showing him mathematical proofs, which he would write down when he awoke. He described one of his dreams as follows:
Discovery of the Scientific Method
René Descartes built much of the framework of the modern scientific method. He wrote down this framework in his work Discourse on Method.
One of his main lines of thought was skepticism – that everything should be doubted until it could be proved.
His four main ideas for scientific progress were:
1. Never accept anything as true until all reasons for doubt can be ruled out.
2. Divide problems into as many parts as possible and necessary to provide an adequate solution.
3. Thoughts should be ordered, starting with the simplest and easiest to know, ascending little by little, and, step by step, to more complex knowledge.
4. Make enumerations so complete, and reviews so general, that nothing is omitted.
Descartes wrote that the basis of the Scientific Method came to him in dreams he had on November 10, 1619.
Proof that our Nerves Transmit Signals Chemically
In 1903 Otto Loewi had the thought that nerve signals were possibly transmitted using chemical instructions. He could not think of how he could prove his new idea.
In 1920 Loewi had a dream about the problem. He woke excitedly during the night and scribbled notes about the dream.
In the morning, he could not remember the dream, and he could not read his nocturnal notes either!
The following night, he dreamed about the problem again. The dream was about an experiment he could use to prove his idea, and this time he remembered it.
He carried out research based on his dream and published the work in 1921, establishing that signalling across synapses was indeed chemical, as he had suspected.
It might seem a little ironic that it took 17 years for subconscious thoughts to come to the surface in the man some scientists now call the father of neuroscience!
Ironic or not, in 1936 the great man was awarded the Nobel Prize for Medicine for the work that came to him in a dream.
The Fossil Fish
Louis Agassiz was the world’s foremost expert on fish species – both current and extinct.
He had been trying to understand the structure of a fossil fish for two weeks, but could make no progress.
Agassiz’s wife wrote about how the solution came to him in the form of dreams over three nights:
He had been striving for two weeks to decipher the somewhat obscure impression of a fossil fish on the stone slab in which it was preserved.
Weary and perplexed, he put his work aside at last, and tried to dismiss it from his mind.
Shortly after, he woke one night persuaded that while asleep he had seen his fish with all the missing features perfectly restored. But when he tried to hold and make fast the image it escaped him. Nevertheless, he went early to work, thinking that on looking anew at the impression he should see something which would put him on the track of his vision.
In vain the blurred record was as blank as ever. The next night he saw the fish again, but with no more satisfactory result. When he awoke it disappeared from his memory as before.
Hoping that the same experience might be repeated, on the third night he placed a pencil and paper beside his bed before going to sleep.
Towards morning the fish reappeared in his dream, confusedly at first, but at last with such distinctness that he had no longer any doubt as to its zoological characters. Still half dreaming, in perfect darkness, he traced these characters on the sheet of paper at the bedside.
In the morning he was surprised to see in his nocturnal sketch features which he thought it impossible the fossil itself should reveal. He hastened to work, and, with his drawing as a guide, succeeded in cutting away the surface of the stone under which portions of the fish proved to be hid-
When wholly exposed it corresponded with his dream and his drawing, and he succeeded in classifying it with ease.
The subconscious mind is very powerful. Provided the conscious mind absorbs plenty of data while awake, the subconscious mind can process and make sense of the data while asleep. Some of the greatest scientific discoveries in history are testament to the importance of sleep and dreams in the operation of our minds.