If I didn’t know better, I would think I rarely dream. But everyone dreams every night; I just don’t remember them.
Sleep scientists have shown that most of our dreams, at least the really vivid ones, occur during Rapid Eye Movement (REM) sleep. Dreaming can also occur in other non-REM stages of sleep. It is not so vivid and less bizarre, with more coherent content, resembling thoughts more closely.
During REM sleep, brain waves are markedly different to other stages (non-REM sleep) and closely resemble those of wakefulness. All voluntary muscles in the body are paralysed to prevent acting out of the dreams, and the eyes move rapidly back and forth. Brain waves can be measured in a sleep laboratory, together with muscle tone and eye movements during a procedure called polysomnography (PSG), then interpreted by a sleep technician to find out the different stages of sleep across the night. This data consistently shows that when someone is woken in REM sleep, vivid dreaming is always reported. The episodes of REM sleep occur systematically, around four to six times a night. The intervals becoming longer as the night goes on. REM sleep makes up about 20-25% of total sleep time but the majority is in the second half of the night.
Since Freud’s work on The Interprepation of Dreams, there has been much debate about the function of dreams.
Freud believed dreams were a gateway into the unconscious mind and could be interpreted as unconscious wishes that had not been fulfilled. This theory dominated the field of mental health for almost a century. However, later research showed that Freudian psychoanalysts gave widely different interpretations of the same dream from the same individual. For this reason, it has been rejected by modern day science. And the fact that the theory cannot make clear predictions that can be tested.
Following this, dreams were not considered to have any function but to a by-product of REM sleep. Sleep researchers Matthew Walker and Murray Raskind have demonstrated that dreams do actually have a function above and beyond those of REM sleep.
Dreams appear to act as a form of psychological resolution. By detaching the emotion from difficult events they can be remembered without reliving the feelings that come with them. During REM sleep, noradrenaline (the neurotransmitter in the brain which triggers anxiety) is inhibited. Simultaneously, emotional and memory circuit are stimulated during dreaming. In this way, painful, emotional experiences can be reprocessed in the absence of anxiety in the sleeping brain. This means we can learn from these experiences without being debilitated by anxiety. With the anxiety disorder post-traumatic stress disorder (PTSD), noradrenaline levels in the brain are too high to allow REM sleep to be maintained. Therefore, the process of stripping away the emotion from traumatic events cannot occur. This leads to the common symptoms of PTSD such as intrusive memories, flashbacks and nightmares.
Humans rely on the ability to read facial expressions to understand other’s emotions and intentions. Used in order to navigate the social world around them. This ability gives humans a survival advantage as they can direct their own behaviour accordingly. There are specific areas in the brain that read and interpret these emotional cues from faces. However, without REM sleep, these circuits lose their ability to decode these signals. REM sleep acts to reset the circuits so they are able to work efficiently each morning. Studies have demonstrated that when participants were deliberately sleep deprived, they lost their ability to accurately read emotional expressions from a set of pictures. Faces were more likely to be perceived as threatening or menacing. Even the pictures which the same individuals had classified as friendly when they were not sleep deprived.
While deep non-REM sleep is involved in memory consolidation, during dreaming these memories are blended together in extremely novel ways. During REM sleep, solutions are often found to problems that may have seemed unsolvable during the waking hours and creative content is often constructed. Research has shown that participants are significantly better at creative problem solving when woken from REM sleep compared to when woken from non-REM sleep and when they were awake, with reports that the solutions just “popped out” effortlessly. During dreaming, connections are made between distantly related information in the brain that is simply not obvious in the waking brain. REM sleep appears to turn our knowledge into wisdom.
Evidence for this problem-solving and creativity function of dreaming has not just come from sleep laboratories; history has provided wonderful examples: Mendeleev came up with the formulation for the periodic table in a dream; Michael Faraday proposed the benzene ring structure after he dreamt of a snake biting its own tail; Mary Shelley was inspired to write “Frankenstein” following a dream; Keith Richards reported composing the opening bars of “Satisfaction” in his sleep; Paul McCartney cited dreaming as the origins of both “Yesterday” and “Let it Be.”
Lucid dreaming is when individuals know they are dreaming and are able to manipulate the experience. Using MRI scanners, the validity of lucid dreaming was established, with participants able to signal to researchers through eye movements during REM sleep that they were about to move their hand in a dream. The areas that then lit up in the brain using the MRI scanner were the same as those that lit up when participants moved their hand when awake. This opens up the possibility that lucid dreaming may be used for creative problem solving to harness dreams’ full potential.
Christabel Majendie December 2022.
Christabel is a Bristol based sleep therapist and consultant, specialising in helping individuals experiencing a wide range of sleep problems. For more information on her work you can visit her website.
Christabel is not a brand ambassador and does not endorse any product of Sleep Well Drinks Limited.