Archive | March, 2015

Sleep and dreams

14 Mar

Psychology has always held a fascination for me which is why I chose this for my bachelors degree. In the first week of Psych 101, our essay was on the architecture of sleep and dreams. I got a 99 on this so I hope you find it interesting and useful ~ ENJOY!

Sleep and Dreams

Dreams are interesting diversions from our waking realities. During the course of the night, our dreams take us on grand adventures, sometimes pleasant and sometimes frightening. While researchers do not conclusively agree on the function of dreams, the point is that sleep and dreams are biologically and physiologically necessary to maintain health. Being deprived of either sleep or dreams results in reduced energy, depression, obesity, compromised immune systems, and slowed reactions to visual stimuli. The importance of sleep and dreams begin with appreciating the sleep cycle, what the brain does during sleep, when dreams occur, and how dreams may differ based on circumstances.

The sleep cycle

The sleep cycle is triggered by the biological clock, following the circadian rhythm, which sends messages to sleep or wake up (Myers, 2013, pp. 92, 97). When it is light out, the pineal gland within the hypothalamus inhibits production of the sleep inducing hormone melatonin, but when it is dark, production is reinstated, thus marking the beginning of the sleep cycle (National Sleep Foundation, n.d., para. 4). The sleep cycle moves between rapid eye movement (REM) and non-rapid eye movement (NREM) stages. Sleep starts with NREM and has three numbered sub-stages. During NREM-1, the sleep is so light it is easy to wake up. In NREM-2, a light sleep occurs. In NREM-3, deep sleep begins and waking up during this stage is very difficult. The final stage is REM, evidenced by the rapid eye movement. These stages cycle approximately every 90 minutes in a somewhat recurrent rhythm with differences between frequency and duration. In the first half of the night, deeper sleep occurs and, in the latter half of the night, REM and light sleep dominate (Walker, 2009).

What the brain does during sleep

Throughout the sleep cycle the brain is active and, depending on the sleep stage, will be depicted by either slow, deep waves or rapid waves of neural activity. During NREM-1, the brain waves start to slow, body temperature begins to drop, and muscles begin to relax. In NREM-2, neural activity is irregular with slow brain wave activity offset by spurts of faster brain waves called spindles. In NREM-3, brain activity is the slowest, marked by slow and deep brain waves. Finally, in REM, brain activity increases and, similar to an awake state, eyes move rapidly, body temperature, blood pressure, heart rate and respiration speed up, and the brainstem blocks messages from the motor cortex leaving muscles relaxed and immovable (Myers, 2013, p.95).

When dreams occur

While some dreams may occur during NREM stages, most dreams occur during REM, which happens at the end of the 90-minute sleep cycle. These dreams are typically vivid, imaginative, and emotional. Throughout the course of the sleep cycle, REM can occur several times and take up as much as 25 percent of the sleeping time (Myers, 2013, pg. 96).

How dream may differ based on circumstance

Dreams have a direct relationship with tasks performed just prior to sleep, with distressing or painful events, and based on location or culture. One example is during NREM-1 sleep, where hynagogic sensations are experienced. This includes the sensation of playing a repetitive game while sleeping (Stickgold, Malia, Maquire, Roddenberry, & O’Connor, 2000.) Other examples are nightmares, dreams that cause strong emotional responses including fear and terror, which typically occur in greater frequency after a traumatic event (Levin & Nielsen, 2007).  Finally, dreams can take on an aspect from reality by incorporating the stimuli into the dream. Examples of this include when hunters and farmers have dreams involving animals (Mestel, 1997) or musicians dreaming twice as much about music than non-musicians (Uga, Lemut, Zampi, Zilli, & Salzurulo, 2006).

The function of dreams: Freud’s theory

In 1900, Dr. Sigmund Freud made what he felt was his most significant and important discovery about dreams. In his book, The Interpretation of Dreams, Freud claimed that dreams were representatives of wishes left unsatisfied, and expressed unconsciously through hidden symbols contained within the objects present in the dream itself. He proposed that inner conflict could be expressed through dreams safely, and that the function of dreams helped to satisfy those unspoken wishes (Myers, 2013, pp. 106-107).

The function of dreams: New theories

In addition to Freud’s theory, new theories about the role dreams play have since emerged and point to four other potential functions of dreaming. The first one suggests that dreams serve to allow the brain to organize and file away facts from the day which in turn leads to increased memory. The second theory is that physiological function is improved because the sleep cycle provides periodic stimulation to the brain’s neural pathways. The third theory proposes that neural activity in the brainstem evokes random visual memories and, together with the limbic system, weaves the visuals into story-like dreams. Finally, there is the theory that dreams are the result of the brain maturing and reflecting its cognitive development (Myers, 2013, p. 108).

The importance of sleep

Sleep deprivation has many consequences, including feelings of fatigue, disorientation, memory loss, and could lead to depression, obesity, and mistakes (Owens, 2013, pp. 99-102). When deprived of REM sleep, sensitivity to pain is increased (Roehrs, Hyde, Blaisdell, Greenwald, Roth, 2006), and after a deprivation period, depending on the length and frequency of deprivation, the brain attempts to repay the sleep debt by adjusting sleep cycle to compensate, thus illustrating the biological need for it (Cartwright, 2013).

While there is no conclusive reason why we dream, sleep supports a fundamental need. Considering that our biological clock triggers the onset of sleep, giving the brain an unconscious outlet for discharging information, the mind processes this information in the form of dreams. This means that sleep and dreams are a necessity for a healthy and balanced life. When sleep is deprived, specifically REM sleep, the impact is with the ability to form new memories. Without adequate sleep, learning new things, and remembering them are greatly impacted (Walker, 2009).

 

References

Cartwright, R. (2013, December 10). Sleep Deprivation. Encyclopedia Brittanica. Retrieved from http://www.britannica.com/EBchecked/topic/548545/sleep/38767/Sleep-deprivation

Levin, R., & Nielsen, T. A. (2007). Disturbed Dreaming, Posttraumatic Stress Disorder, and Affect Distress: A Review and Neurocognitive Model. Psychological Bulletin, 133(3), 482-528.

Mestel, R. (1997, April 26). Get real, Siggi – Freud would have been furious – hard-nosed pragmatists are invading the fabulous dream industry he founded. New Scientist. Retrieved from http://www.newscientist.com/article/mg15420799.700-get-real-siggi–freud-would-have-been-furious–hardnosed-pragmatists-are-invading-the-fabulous-dream-industry-he-founded.html

Myers, D. (2013). Psychology in modules, (10th ed.). New York: Worth.

National Sleep Foundation. (n.d.) Retrieved March 6, 2015 from http://sleepfoundation.org/sleep-topics/melatonin-and-sleep

Roehrs, T., Hyde, M., Blaisdell, B., Greenwald, M., Roth, T. (2006) Sleep loss and REM sleep loss are hyperalgesic. SLEEP, 29(2), 145-151.

Stickgold, R., Malia, A., Maquire, D., Roddenberry, D., & O’Connor, M. (2000, October 13). Replaying the game: Hypnogogic images in normal and amnesics. Retrieved from http://www.bostonneuropsa.net/PDF%20Files/Stickgold/Tetris_Science.pdf

Uga, V., Lemut, M. C., Zampi, C., Zilli, I., & Salzurulo, P. (2006). Music in dreams. Retrieved from http://web.mit.edu/dmalt/Public/9.10/02sdarticle.pdf

Walker, M. (2009). The Role of Sleep in Cognition and Emotion. The Year in Cognitive Neuroscience (2009). 168-197. Doi: 10.1111.j.1749-6632-2009.04416.x Retrieved from http://walkerlab.berkeley.edu/reprints/Walker_NYAS_2009.pdf