Words by: Isaac Hallé

For millennia humans have sought to understand the meaning of the visual auditory experiences which occur during sleep – otherwise known as dreams. The Ancient Egyptians considered them messages from the Gods, during the scientific revolution and beginnings of psychology, Freud in his seminal work, On the Interpretation of Dreams referred to dreams as “A Royal Road to the unconscious”. In the wake of modern scientific techniques and better understanding of the brain during sleep, we will explore what exactly are dreams? And do they really mean anything?

Dreams occur during the Rapid Eye Movement (REM) stage of sleep. Several stages of REM cycle during sleep accounting for around 25% of sleep in adults. Babies experience up to 80% of REM stage sleep which decreases over time with age. But, if dream sleep is so prevalent, why do we remember so few, if any? Reduction in the chemical norepinephrine during sleep makes it more difficult to form memories during sleep. Serotonin levels also fall, leaving the effect upon waking that the dream experienced was profound and meaningful, perhaps explaining why so many have sought answers to dreams from Gods, Sages… and the internet.

During Rapid Eye Movement sleep the Amygdala – the hippocampus and amygdala – the emotional centers of the brain,  are activated whilst the prefrontal cortex, the part of the brain responsible for executive function and rationality is inactive. Analysis of the electrical signals produced through neuronal activation (better known as brain waves) shows that unlike the slow brain wave activity of deep Non-REM sleep, during Rapid Eye Movement Sleep the brain is equally as lively as during waking activity, all that prevents the body from moving is part of the brain stem, known as the PONS. The PONS of those suffering REM disorder, however, fails to prevent movement and thus dreams are acted out by such individuals with sometimes dangerous effect.

Exactly why humans and mammals in general dream, is not yet well understood. Various theories have attempted to solve this mystery. The modern popular scientific view regards dreams as not inherently meaningful, a mere by–product of dream sleep function. The most notable of these functions is memory. The neuronal activation during REM sleep is said to be a method of the brain consolidating already formed memories and filtering out those which are less useful. This supports and links to the Continuity Hypothesis of Dreaming which explains the commonality of imagery and content from the dreamer’s waking life. Whilst the continuity Hypothesis is broadly accepted there is some dispute on the meaning of dreams. 

Dreams undoubtedly inform us in a clinical perspective. Recurring dreams are a recognized symptom of Post-Traumatic Stress Disorder and whilst this phenomenon is yet to be explained there is an exciting explanation posited by dream expert Professor Mathew Walker. Participants in a study were shown to less emotionally reactive to upsetting imagery following REM sleep compared to a control group who did not have dream sleep. Walker believes that dreams may serve as an “overnight therapy” for emotional experiences. This would thus enable us to move forward from tragedy, sadness and trauma. We don’t cry over the same memories that once brought tears. Dream sleep may be why. This argument carries more weight still when the recurring dreams associated with PTSD are mentioned. Perhaps some failure in this emotional consolidation results in repeated attempts by the brain in sleep to resolve such trauma, resulting in repeated content and recurring nightmares.

More research is necessary to understand such a mechanism; however, various studies do support links between psychological emotional states in waking life and dream content. Patients undergoing psychotherapy have been found to change alongside their dream content. Dream Therapy such as Image Rehearsal Therapy or IRT, involves retelling the dream narrative and reimagining it in a new light and has been shown to effectively treat PTSD and mental health problems. Some small studies have even found that dream content has positive effects on people. Dreams of ex-husbands reduced depression in female divorcees in 6-month follow ups. Similar correlations have been found with those giving up smoking dreaming of cigarettes. Whilst the weight of such research is largely controversial and must be taken with a pinch of salt, the suggested links between dream content and emotional consolidation are exciting and could prove invaluable to the science of psychology and treatment of PTSD.

All we can say for sure is the science of dreams is not something to sleep on.

Image Credit: Petr Kratochvil 

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