At the turn of the 21st century, neuroscientist Mark Solms developed a theory that dreams protect sleep by preventing us from constantly waking up to try to achieve our goals.
Dreaming and REM Sleep
In the beginning of the twentieth century, scientists learned that they could study people’s brain waves by attaching electrodes to their heads. In 1953, Eugene Aserinksy and Nathaniel Kleinman discovered that when we sleep, we periodically go through a stage in which our eyes make rapid, jerky movements. This stage of sleep came to be known as the Rapid Eye Movement (REM) stage of sleep.
Scientists found that during the REM stage, parts of the brain become very active. The metabolic rate increases.
However, the most interesting thing they discovered about this stage of sleep had to do with dreams. Studies have shown that if you wake someone up in the middle of the REM sleep stage, there is a 70 to 95 percent chance that they will say they have just been dreaming. However, if you wake them up during any of the other four stages of sleep, known collectively as non- rapid eye movement (NREM sleep), there is only a 5 to 10 percent chance that they will say they have been dreaming.
This led scientists to conclude that REM sleep causes dreams. Therefore, if you know why people have REM sleep, you will know why they dream.
What Causes REM Sleep?
After REM sleep was discovered, scientists experimented on cats to find out which part of the brain causes this stage of sleep. In 1962, Michel Jouvet discovered that cats with damage to the pons, a small region of the brain stem, do not have REM sleep. Meanwhile, damage to the higher levels of the brain does not seem to have any effect on REM sleep. Thus, it was determined that REM sleep is produced in the pons.
The Activation Synthesis Theory of Dreaming
In the 1970s, J. Allan Hobson and Robert W. McCarley developed the activation synthesis theory of dreaming. This theory states that dreams are produced by random stimuli from the pons. The forebrain, the “thinking” part of the brain, receives these stimuli and then makes up stories to make sense of them. These stories are what we call dreams.
We Dream Outside of REM Sleep
The activation synthesis theory is based on the idea, which has been shared by many, that dreams are an aspect of REM sleep. Therefore, if REM sleep is caused by activity in the pons, then dreams are caused by activity in the pons.
However, in 1962, cognitive psychologist David Foulkes performed a sleep study. In such studies, subjects are usually woken up at different ages of sleep and asked if they have been dreaming. However, instead of asking subjects if they had been dreaming, Foulkes asked, “What was passing through your mind?” Half of the subjects who were awakened during NREM sleep reported complex mental activities that could have been considered dreams.
While the average NREM dream is less vivid than the average REM dream, between 5 and 30 percent of NREM dreams can’t be distinguished from REM dreams. Considering that about three quarters of the time we spend sleeping is spent in the NREM stages, this means that about one quarter, at least, of vivid dreams take place during NREM sleep.
Could some of Foulkes’ subjects who claimed to have been dreaming vividly in NREM sleep really been dreaming during an earlier REM stage and been mistaken about when they dreamed? In many cases, that would not have been possible. Foulkes found that subjects would report dreams even before they had entered the first stage of REM sleep.
Later research has shown that if someone is awakened during the first few minutes of sleep, they will report a dream 50 to 70 percent of the time, and the dream will be no different from an REM dream, except for the length.
People Who Don’t Have REM Sleep Still Dream/People Who Don’t Dream Still Have REM Sleep
At the end of the 20th century, Solms studied records of cases in which people suffered damage to the pons and therefore lost most or all of their ability to experience REM sleep. He found 26 such cases. He found that only one of these people said that they had also stopped dreaming
Solms also studied records of cases in which people stopped dreaming after suffering brain damage. There were 111 such cases. In all but one case, there was no damage at all to the pons. A completely different part of the brain was injured.
Further studies have shown that in these cases, people still experience REM sleep, even though they no longer dream. To ensure that they haven’t simply forgotten their dreams, patients have been awakened during REM sleep to check that they haven’t been dreaming.
Where Dreams are Made
Solms then performed a study of his own neurosurgical patients in hospitals in London and Johannesburg. For four years, he asked every patient if they had noticed any changes to their dreams after they had suffered brain damage. For a control group, he used patients who had been referred to him but had been found not to have any neurological damage.
Patients reported four types of major changes to their dreams:
• Some patients stopped dreaming altogether.• Some patients stopped seeing things in their dreams• Some patients started having recurring nightmares• Some patients began to confuse dreams and reality
By looking at where these patients’ brains had been injured, Solms was able to find which parts of the brain have a part in the dreaming process.
Dreams are Made in the Forebrain
Solms found that while REM sleep is produced by the pons in the brainstem, dreams are produced in two different areas of the forebrain.
One of these areas is in a part of the frontal lobes just above the eyes. This area contains a pathway through which a chemical called dopamine travels from the middle of the brain to the higher parts of the brain. When someone suffers damage to the dopamine pathway, they continue to have REM sleep, but they stop dreaming.
In the 1940s and 1950s, a study was done of over 300 people who had undergone frontal lobotomies. It was found that these people tended to have very few or almost no dreams.
Drugs such as L-Dopa, which stimulate the dopamine pathway, cause people to have vivid dreams. Drugs such as haloperidol, which suppress the dopamine pathway, can cause frequent, excessively vivid dreams to stop.
The second area of the brain that is responsible for dreaming is the occipito-temporo-parietal (OTP) junction, which is located just behind and above the ears. We use this area of the brain for the highest levels of thinking. This includes taking concrete information and converting into abstract ideas. If someone experiences damage to this part of the brain, they cannot dream at all.
How Dreams Protect Sleep
Solms found that the activity of the pons during REM sleep is just one of many different triggers, including L-DOPA and some stimulant drugs, which can cause people to dream. These triggers all have one thing in common – they create a state of arousal.
However, these triggers only cause people to dream when they activate the dopamine pathway. If this pathway is removed, they can’t dream.
The main purpose of the dopamine pathway is to make us try to achieve our goals. People who suffer damage to this pathway not only stop dreaming, they also lose the motivation to achieve things in their waking lives.
Solms also found that the dorsolateral frontal convexity, a part of the frontal lobes that is one of the most active areas of the brain when we are awake, becomes completely inactive when we dream. This area of the brain is connected to the motor system. It is the area of the brain where thoughts are converted to action.
Brain activity during waking life is concentrated in the dorsolateral frontal cavity. However, when we dream, it is concentrated in the OTP region, the part of the brain that houses our memory and our perceptual systems.
This means that when we sleep, our wishes are not converted to actions. Instead, our intentions to act are transferred away from the motor systems and toward our perceptual systems, where they are transformed into internal images. In addition, because parts of the limbic system that allow us to reflect on our experiences become inactive during sleep, we mistake these images for reality.
In this way, we are prevented from physically perform goal-seeking actions while we sleep. Thus, our sleep is protected.
Freud’s Wish-Fulfillment Theory of Dreams
Solms said that his theory provides a neurological basis for Freud’s theory that dreams represent unfulfilled wishes. Freud believed that dreams were a way to satisfy desires that could not be satisfied in waking life.