The Science of Dreams and Nightmares September Edition 2021
Introduction Dear readers, “Have you ever had a dream that you were so sure was real? What if you were unable to wake from that dream? How would you know the difference between the dream world and the real world?” – Morpheus, The Matrix. Dreams are a very peculiar phenomenon occurring in the depths of our minds. Have you ever had a dream? Are you wondering what dreams are? This edition will focus on the study of dreams, oneirology. We will start with the introduction of dreaming and sleeping. Subsequently, there will be a special focus on lucid dreams and how to induce them. Unfortunately, not every dream is sweet and therefore we will also shed some more light on the concept of nightmares, their causes and their treatment. Lastly, we will conclude with an article about the curious phenomenon of sleepwalking and how to deal with sleepwalkers. Enjoy reading this edition of Science! Monthly!
Yong Xin Cao Science Coordinator 2021/2022
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Sweet dreams – Can you remember them? “Sweet dreams”, a very common phrase that most have heard from their parents during their childhood. In the past, you might not have put much thought into it, but now you may be wondering what dreams are. To understand dreams, it is important to comprehend the stages of sleep.
Sleep cycles1 Humans sleep to rest their bodies. It keeps their mind and body refreshed after awakening. Sleep is not uniform but is made up of several rounds of sleep cycles. Sleep is composed of 4 stages, and during a typical night, a person goes through 4 to 6 cycles. The length of these cycles varies, however, on average they are about 90 minutes each. A sleep cycle consists of 3 Non-Rapid Eye Movement (NREM) stages followed by 1 Rapid Eye Movement (REM) stage. The sleep cycle starts with stage N1. This is the phase where people doze off. The body and brain activities start slowing down, however, the body is not fully relaxed yet. During this stage, it is easy to wake someone up. If a person is not disturbed during this stage, they move into the next phase, stage N2. The body enters a more relaxed state-the muscles relax and both the heart and breathing rate slow down. A slight drop in body temperature will occur as well. Furthermore, eye movement stops and the brain waves slow down. However, there are short bursts of brainwave activity, which serve as a resistance to waking up. After stage N2 follows stage N3 which is characterized by delta waves in the brain. It is more difficult to wake someone up in this phase. This period is defined by reduced muscle tone, breathing rate and pulses, allowing full body recovery. Stage 4, also known as REM sleep, concludes the sleep cycle. During this phase, brain activities are near activity levels like your awake state. The whole body will experience atonia, a temporary paralysis of the muscles. Only the muscles in the eyes and those that control breathing are exempted. The eyes are moving very quickly as the name of this stage suggests. It is hypothesized that REM sleep is relevant to cognitive functions like learning, creativity, and memory. In general, people tend to enter REM sleep after sleeping for about 90 minutes. As the night continues, this phase gets longer. In table 1 the characteristics and stages of a sleep cycle are displayed. These stages are determined based on brain activity during the sleeping hours and show different patterns in each stage. Stages Stage 1 2 3 4
of the sleep cycle Type Duration NREM 1-5 min NREM 10-60 min NREM 20-40 min REM 10-60 min
Other names N1 N2 N3; slow-wave sleep; delta sleep; deep sleep REM sleep
Table 1: characteristics and stages of a standard sleep cycle.
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What is a dream?2 A dream is a progression of images, feelings, thoughts, and ideas that occur automatically in the brain during specific periods of sleep. They usually occur during REM phase, when the cerebrum is highly active and resembles being conscious. However, while less frequent, dreams can appear during NREM sleep as well. Generally, people have 3 to5 dreams every night. They can be different in duration extending from a few minutes, up to 20-30 minutes. Image 1: Dreaming
Remembering dreams3 Dreams are easily forgotten. About 95% of the dreams are forgotten by the time people wake up. Studies4 indicate that people are more likely to remember their dreams when they are woken up directly after REM sleep. A study conducted by Marzano et al. gives us more insight into how humans remember their dreams. The brain experiences 4 types of electrical brain waves: alpha, beta, delta, and theta, with each having their own different speed of oscillating electrical voltages. Together they form the electroencephalography (EEG). It has been discovered that those who have a higher number of low-frequency theta waves in the frontal lobes are more often able to remember their dreams. This increased activity of theta waves is similar to the activity related to the successful encoding and retrieval of memories while awake. Thus, this neurological mechanism in the frontal cortex that is employed while dreaming and recalling those dreams is the same as when memories are retrieved and constructed during the waking period4. Other studies also showed that vivid and emotionally intense dreams are linked to the amygdala and hippocampus. The amygdala plays a role in processing and memorizing emotional reactions. The hippocampus has important memory functions. It can consolidate information from short- to long-term memory5. Dreams seem to be closely related to our emotions and they seem to support the process of these emotions by encoding and constructing memories. While the dream can be perceived as surreal, the attached emotions are certainly real3.
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The Lore of Lucid Dreams Lucid dreams are a type of dreams where the dreamer becomes aware that they are dreaming. At some point, the dreamer may have control over their dreams to some degree. People were already aware of the concept of lucid dreaming in the fourth century Before the Common Era (BCE) as writings of Aristotle about this subject have been found. In the 1970s scientists discovered that lucid dreams are mostly common during Rapid Eye Movement (REM) sleep when most dreaming occurs. Almost 50 per cent of the people have experienced one lucid dream with roughly 10% experiencing them more than once in a month6.
How to induce lucid dreams?7,8 There have been several methods designed to train lucid dreaming. These methods focus on training your mind to detect your own consciousness when you enter REM sleep. 1. Reality testing This mental training method requires you to pause at different times of the day and consider whether you’re dreaming. This can be achieved by trying to do something impossible while being awake, e.g., trying to put one of your hands through your other hand’s palm, or something that is often difficult to conduct when dreaming. The latter could be checking your own reflection and seeing whether it looks normal, checking whether time changes quicker than normal, or reading a page in a book. Reality testing can strengthen metacognition, also referred to as awareness of one’s own thought processes. A study by Corlett et al. (2014) has revealed that one’s metacognition is at similar levels during waking and dreaming hours. If metacognition during waking life will be strengthened, this could lead to a higher metacognition during dreams as well. 2. Wake-back-to-bed Wake-back-to-bed (WBTB) is a technique that involves entering REM sleep while still conscious. Generally, you wake up after 5 hours of sleep and stay briefly awake. Thereafter, you go to bed once more and try to enter a REM sleep period. It is suggested that the period of alert wakefulness makes lucid dreaming more likely, rather than the activity10.
Image 2: set your alarm clock EPSA – European Pharmaceutical Students’ Association
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3. Mnemonic induction of lucid dreams One of the first methods of scientific research to induce lucid dreams is called Mnemonic induction of lucid dreams (MILD) Created by LaBerge in 198011, this technique involves setting intentions to do something in the future, also known as prospective memory. People who want to induce lucid dreams this way will set an alarm to wake up after 5 hours of sleep. During the time they wake up, they tell themselves to remember the next time they dream. A prospective study conducted in Australia found that the combination of MILD, WBTB and reality testing works the best12.
4. Keeping a dream diary One of the most popular methods is keeping dream diaries. You can write your dreams in these diaries. This way, you’re forced to focus on your dreams and remember them. Furthermore, this will support your recognition of dream signs and enhance your awareness of dreams. It is recommended to write your dreams as soon as you wake up as your memory will fade with time. Whether this works on inducing lucid dreams is controversial.
Image 3: Keeping your dream diary
5. Wake-initiated lucid dreaming Wake-initiated lucid dreaming (WILD) involves entering a dream directly from waking life, thereby the mind will stay conscious while the body sleeps. This method requires you to relax until you experience a (hypnagogic) hallucination. Hypnagogic hallucinations, also known as waking dreams, occur when people are drifting off to sleep. These hallucinations are presented as seeing, feeling, hearing, or smelling something that is not present.
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Advantages of lucid dreams7,8 Lucid dreams can reduce anxiety in real life. The sense of a certain amount of control during the lucid dream might last during your waking life. Therefore, this might strengthen the dreamer. In addition, they may also help to overcome nightmares in the same way, by having control. The dreamer will also be able to recognise more easily that nightmares aren’t real. In imagery rehearsal therapy, lucid dreaming is often used and helps you reimagine a nightmare with a different, more pleasant storyline. In combination with Cognitive Behavioral Therapy (CBT), Imagery Rehearsal Therapy (IRT) with lucid dreaming induction can improve dream control.
Disadvantages of lucid dreams7,8 The downside of these peculiar dreams is the decrease in the quality of sleep. Lucid dreams are usually very vivid. Paying a lot of attention to these dreams might wake you up roughly. Furthermore, it will also make it harder to get back to sleep once you’re awake. In addition, using lucid induction methods like WBTB and MILD can also reduce sleep quality. In people who have mental disorders, these dreams may blur the line between reality and imagination. Derealization, characterized as the feeling that things are not real, can occur as well. There is a risk for sleep paralysis too. Lastly, the sleep interruptions consequently to the induction techniques can increase depressive symptoms.
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Afraid of Nightmares? Nightmares are negative, distressing dreams which cause disturbing emotions such as fear and anxiety13. They occur very commonly. About 50%14 of the children report at least one time having nightmares. Approximately 85% of the adults have a nightmare at least once a year15,16. The prevalence of nightmares can vary across cultures.
Image 4: Nightmare
Clinical features Nightmares are vivid dreams that are often well-remembered, and which also cause awakening15. The themes that are most involved in nightmares are death, physical violence and being chased16. Nightmares are associated with an increased sense of awareness. Clinical features that often appear are palpitations, sweating, increased blood pressure, increased heart rate, and symptoms of panic or anxiety upon awakening. A nightmare is also a dream and just like dreams, they generally appear during Rapid Eye Movement (REM) sleep. However, nightmares that are associated with posttraumatic stress disorder (PTSD) commonly occur during N1/N2 sleep as well, thus occurring both early and late during one’s sleep (cycle)15.
Image 5: anxiety
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Causes of nightmares15,17,18 Nightmares are caused by stress, fear, trauma, illness, medication, sleep disorders, and emotional difficulties13. Here, trauma and medication will be elucidated. •
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Trauma: trauma can be either physical or emotional. A very well-known disorder that can be considered a trauma is posttraumatic stress disorder (PTSD). PTSD features nightmares with recurring experiences of a traumatic event that had happened in the past. These nightmares can not only occur during REM sleep, but also during sleep onset. The latter results in insomnia and sleep disruption. Medication: it has been suggested that medication can generate nightmares. The following drug classes are implicated to cause nightmares: o Antidepressants: nightmares are usually associated with medication withdrawal. While the mechanism has not been proved yet, a possible explanation for this nightmare-inducing effect is that REM sleep is delayed and related to cholinergic rebound and a stronger dream activity. o Antimicrobials: It is suggested that certain antimicrobials, for example, ciprofloxacin, erythromycin, ganciclovir, induce nightmares through modulation of inflammatory cytokines (interleukin-1B, tumour necrosis factor-alpha, prostaglandin E2) that plays a role in sleep regulation. o Dopamine agonists
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Management of nightmares15 The management of nightmares consists of non-pharmacological and pharmacological treatment strategies. Non-pharmacologic therapies Non-pharmacological treatment consists of: • Lifestyle modification • Good sleep hygiene • Withdrawal of medication causing nightmares • Treatment of psychiatric comorbidities and underlying conditions • Nightmare-focused psychotherapy o o o
Image 6: structure of prazosin
Imagery rehearsal therapy Cognitive-behavioral therapy for insomnia Other specialized techniques
Pharmacologic therapies The best-known pharmacological therapy for nightmares is prazosin. Prazosin is an alpha-1 adrenergic receptor antagonist and is often the preferred first-line therapy when medication is required. A meta-analysis conducted in 2020 showed that prazosin was more effective than placebo at improving nightmares in patients with PTSD. However, it should be noted that most patients were concurrently treated with psychotherapy and psychiatric drugs. There is also heterogeneity between studies19. Prazosin is thought to reduce nightmares by its ability to antagonize the noradrenergic nervous system, which is associated with the hyperarousal state of PTSD. Patients suffering from PTSD have an increased sensitivity for the noradrenergic system and increased levels of noradrenaline in the cerebrospinal fluid. Prazosin is typically prescribed at 1 mg and should be taken just before bedtime. It is usually titrated up to 10 mg. The effect occurs after a few weeks, most often by week 8. Data of other pharmacological therapies is very limited. Drugs that might have a possible benefit are trazodone, clonidine, topiramate, gabapentin, terazosin and atypical antipsychotics like olanzapine and risperidone.
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Sleepwalking: An arousal disorder Sleepwalking, also referred to as somnambulism, is an arousal disorder. When someone is sleepwalking, they usually walk or conduct complex activities while not fully awake20. The estimated lifetime 21,22 prevalence is 6.9% . It is more common in children than in adults, but it can also appear de novo during adulthood. However, the preferred occurrence is usually associated with medications and neurodegenerative diseases22. People can grow out of it by the time they reach puberty. Sometimes, however, it will persist into adulthood20.
Image 7: Sleepwalking
Sleepwalking – what happens?23 What happens when a person is sleepwalking differs among individuals? Some might just sit up in bed and look around. They will appear confused. Others may get out of bed and start walking. They can either eat or start dressing and may look agitated. In very extreme cases, people conduct complex activities like driving a car. Sleepwalkers look like they’re awake as their eyes are usually open. However, you will notice that sleepwalkers often look straight through people, thereby not recognizing them. During their sleepwalk, people might respond partially, and they usually say things that don’t make sense. Episodes of sleepwalking usually last up to 10 minutes. Memories of their sleepwalking episodes are usually gone by the time they have awoken23. Sleepwalking is usually a benign condition. However, in some cases, it can be harmful and result in severe injuries (e.g., falling from great heights or walking through glass windows).
What is the underlying pathophysiology?22 Sleepwalking is associated with NREM sleep. It is indicated that there is a decrease in localized cerebral blood flow in the parietal and frontal areas of sleepwalking patients. Furthermore, there seems to be restricted perfusion in the dorsolateral prefrontal cortex and insula, a small region of the cerebral cortex, which may be congruous with clinical signs of these sleepwalking episodes. Changes in regional cerebral blood flow occurring while sleepwalking can be related to functional problems during the waking time.
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Why do some people sleepwalk?20,23 It is unknown what exactly causes people to sleepwalk, however, there are some indications that people are more likely to sleepwalk if other close family members have or had this sleepwalking behaviour or night terrors. Some triggers for sleepwalking are insufficient sleep, stress, anxiety, alcohol abuse, infections, recreational drugs abuse, certain medications, obstructive sleep apnea, restless legs syndrome, and suddenly waking up from deep sleep.
How should sleepwalking be treated?20,23 The management of sleepwalking is depending on the age of the patient, the frequency of occurrence, and how dangerous and severe these episodes are. Sleepwalking often does not require an active treatment because episodes are rare and it is usually not dangerous. However, it is sometimes recommended to lower safety risks if there is a sleepwalker around. Ways to reduce the safety risks and eliminate potential harms are: • Hiding sharp objects and weapons • Closing doors and windows • Installing lights with sensors • Removing objects that can make people trip Currently, there is no medication approved for the treatment of sleepwalking. However, there is some clinical experience suggesting some benefit of gamma-aminobutyric acid (GABA) stimulating agents if taken in an hour before going to bed. Non-pharmacological therapy like Cognitive Behavioral Therapy (CBT) or hypnotherapy can be helpful as well along with some lifestyle changes.
Should you wake a person who is sleepwalking?20 The best thing to do is to keep the sleepwalking person safe. It is recommended to gently guide them back to bed. Sleepwalkers will often go back to sleep once more if they remain undisturbed. In some cases, gently waking these people after their episodes will prevent another episode from occurring after they go to bed again. It is not advised to shout or startle the sleepwalker. Neither should you physically restrain them, if they’re not in danger, as they can be agitated.
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References [1] Sleep Foundation. Stages of Sleep. [Online]. Available at: https://www.sleepfoundation.org/how-sleep-works/stages-of-sleep. [Accessed at: 2021 August 27]. [2] Hilaris Publisher. Journal of Oncology Translational Research: Dream. [Online]. Available at: https://www.hilarispublisher.com/open-access-journals/dream11764.html. [Accessed at: 2021 August 27]. [3] Scientific American. The Science Behind Dreaming. [Online]. Available at: https://www.scientificamerican.com/article/the-science-behind-dreaming/. [Accessed at: 2021 August 27]. [4] Nielsen TA. A review of mentation in REM and NREM sleep: "covert" REM sleep as a possible reconciliation of two opposing models. Behav Brain Sci. 2000 Dec;23(6):851-66; discussion 904-1121. Erratum in: Behav Brain Sci 2001 Jun;24(3):576. [5] De Gennaro, L., Cipolli, C., Cherubini, A., Assogna, F., Cacciari, C., Marzano, C., Curcio, G., Ferrara, M., Caltagirone, C. and Spalletta, G. (2011), Amygdala and hippocampus volumetry and diffusivity in relation to dreaming. Hum. Brain Mapp., 32: 1458-1470. [6] Science. Scientists entered people’ dreams and got them ‘talking’. [Online]. Available at: https://www.sciencemag.org/news/2021/02/scientists-entered-peoplesdreams-and-got-them-talking. [Accessed at: 2021 August 28]. [7] WebMD. Lucid Dreams. [Online]. Available at: https://www.webmd.com/sleepdisorders/lucid-dreams-overview. [Accessed at: 2021 August 28]. [8] Healthline. 5 Techniques to Try for Lucid Dreaming. [Online]. Available at: https://www.healthline.com/health/healthy-sleep/how-to-lucid-dream#how-towake-up. [Accessed at: 2021 August 28]. [9] Corlett PR, Canavan SV, Nahum L, Appah F, Morgan PT. Dreams, reality and memory: confabulations in lucid dreamers implicate reality-monitoring dysfunction in dream consciousness. Cogn Neuropsychiatry. 2014;19(6):540-553. [10] LaBerge S. Lucid dreaming as a learnable skill: A case study. Percept Mot Skills. 1980;51(3):1039–42. [11] LaBerge S, LaMarca K, Baird B. Pre-sleep treatment with galantamine stimulates lucid dreaming: A double-blind, placebo-controlled, crossover study. PLoS One. 2018;13(8):e0201246. [12] Aspy, D. , Delfabbro, P. , Proeve, M. , Mohr, P. & (2017). Reality Testing and the Mnemonic Induction of Lucid Dreams. Dreaming, 27 (3), 206-231. [13] MedicalNewsToday. What does it mean when we dream? [Online]. Available at: https://www.medicalnewstoday.com/articles/284378#what-are-dreams. [Accessed at: 2021 August 28]. [14] Gauchat A, Séguin JR, Zadra A. Prevalence and correlates of disturbed dreaming in children. Pathol Biol (Paris). 2014 Oct;62(5):311-8. [15] UpToDate. Nightmares and nightmare disorder in adults. [Online]. Available at: https://www-uptodate-com.proxy.library.uu.nl/contents/nightmares-and-nightmaredisorder-inadults?search=dreams&source=search_result&selectedTitle=1~150&usage_type=defa ult&display_rank=1#H2376493068. [Accessed at: 2021 August 29]. EPSA – European Pharmaceutical Students’ Association
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[16] Levin R, Nielsen TA. Disturbed dreaming, posttraumatic stress disorder, and affect distress: a review and neurocognitive model. Psychol Bull. 2007 May;133(3):482-528. [17] Thompson DF, Pierce DR. Drug-induced nightmares. Ann Pharmacother. 1999 Jan;33(1):93-8. [18] Healthline. Different Types of Dreams and What They May Mean About You. [Online]. Available at: https://www.healthline.com/health/types-of-dreams#nightmares. [Accessed at: 2021 August 29]. [19] Yücel DE, van Emmerik AAP, Souama C, Lancee J. Comparative efficacy of imagery rehearsal therapy and prazosin in the treatment of trauma-related nightmares in adults: A meta-analysis of randomized controlled trials. Sleep Med Rev. 2020 Apr;50:101248. [20] NHS. Sleepwalking. [Online]. Available at: https://www.nhs.uk/conditions/sleepwalking/. [Accessed at: 2021 August 29]. [21] Stallman HM, Kohler M. Prevalence of Sleepwalking: A Systematic Review and Meta-Analysis. PLoS One. 2016;11(11):e0164769. [22] Zergham AS, Chauhan Z. Somnambulism. [Updated 2021 Jun 7]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK559001/ [23] Sleep Foundation. Sleepwalking. [Online]. Available at: https://www.sleepfoundation.org/parasomnias/sleepwalking. [Accessed at: 2021 August 29].
References for pictures: Front page image: https://unsplash.com/photos/09znJJdtZFc Image 1: https://unsplash.com/photos/Z9m8qLIXqIU from: Andriyko Podilnyk Image 2: https://unsplash.com/photos/CxRBtNe243k from: Abdul A Image 3: https://unsplash.com/photos/Ge4nB83WNpg from: Kelly Sikkema Image 4: https://unsplash.com/photos/UwB9VI4Rs2A from: Toa Heftiba Image 5: https://unsplash.com/photos/zt8PJ6LT9Uw from: Hailey Kaen Image 6: https://pubchem.ncbi.nlm.nih.gov/compound/Prazosin#section=2D-Structure Image 7: https://pixabay.com/images/search/sleepwalking/
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