The nervous system is an extremely elaborate biological machine. Without question, the nervous system is a system so intricate and comprehensive that professionals in the field of medicine to this day do not have a “complete picture” of each of the working details of the human nervous system. Of these different mechanisms, perhaps the one most riddled with speculation, is the mechanism of sleep. In discussing regulatory process, sleep is perhaps one of the most essential to the healthy upkeep of the human nervous system. This process is such a necessary behavior that without it, the nervous system, and the overall health of the individual in question can become compromised (to the point of fatality) without it. The Nervous System
The central nervous system is made up of two major components, the brain and the spinal cord. The spinal cord connects to the brain, and is the main messenger component to the rest of the body from the brain. There are several different parts of the brain including the hypothalamus, the thalamus, the corpus callosum, and the cerebellum (“The Central Nervous System”, 2009). The hypothalamus is above the spinal cord, and regulates the consumption of food and water. It also “controls the release of sex hormones from the pituitary gland” (“The Central Nervous System”, 2009). The thalamus is responsible for passing on information from the senses to the brain. The corpus callosum connects the two hemispheres of the brain and helps with communication. The cerebellum stores procedural memory, and the cortex helps to make decisions and solve problems. The left hemisphere of the brain controls different aspects of the human body than the right hemisphere.
The left hemisphere controls the right side of the body, and regulates speech, language, comprehension, analysis, calculations, time, sequencing, and recognition of words, letters and numbers (“The Central Nervous System”, 2009). The right hemisphere controls the left side of the body, and regulates creativity, spatial ability, context/perception, and recognition of faces, places, and objects. A neurotransmitter is a chemical message that acts between the neurons in the brain. A neuron consists of an axon, dendrites, a cell body, and the axon terminal. The dendrites are branch-like structures off of the cell body and the location of information is received. The axon terminal reaches out to other nerve cells to pass information over the synapse, which is a small gap between the dendrites and axon terminal (“The Central Nervous System”, 2009)..
For any neurons to communicate with one another, there must be an electrical impulse to pass the information over the synapse. “This electrical impulse is made at the head of the axon and then travels down towards the axon terminal, where it causes channel proteins to open and allow calcium ions through the cell membrane and into the neuron. Once the calcium ions are inside the neuron, they bind with vesicles and cause them to meet the cell membrane where they fuse and the neurotransmitters are released. The neurotransmitters then diffuse across the synapse and bind with receptors on the new neuron” (“The Central Nervous System”, 2009). When this binding occurs, a response is triggered. Effects of Fear, Aggression, and Anxiety
Fear, aggression, and anxiety can all have an immensely large effect on one’s sleeping habits. An ongoing fear or phobia can cause an individual to lose sleep, which in turn, decreases their function the next day. Fear can also inhibit bad dreams throughout the night, which could also cause the individual to wake up periodically throughout the night and not receive any REM sleep. Aggression can also affect sleep as well. If an individual already has sleep problems, such as sleep apnea or insomnia, this can cause aggression to worsen. It also is the other way around: if a person has an ongoing aggression, it can cause more sleep problems than before. Anxiety can also cause problems with normal sleep hygiene. Anxiety could possibly be the cause of one’s sleep apnea or insomnia. There is a cycle that some may go through when trying to sleep. First, you are lying in bed having difficulty getting to sleep.
Then, you realize that you are still awake and should be sleeping; this is when the anxiety kicks in. The body kicks in the fight-or-flight mechanism, and the sympathetic nervous system shifts on, and the body starts to produce adrenalin due to a false perception of a threat, which prevents sleep. Then you are back to the start where it is difficult for you to fall asleep. Lack of adequate sleep can make it difficult to receive, and remember information. Sleepless nights can result in overworked neurons to no longer function well. To stimulate the brain regions used in learning, we can depend on rapid-eye-movement (REM) sleep. During REM sleep, cells in the pons send messages that inhibit the motor neurons that control the body’s large muscles (Kalat, 2013).
Slow-wave sleep (SWS) can also play a significant role in memory. SWS can increase restorative processes during sleep. Slow waves indicate that neuronal activity is highly synchronized (Kalat, 2013). Depriving a person of sleep can impair verbal learning, especially early in the night. Depriving a person of sleep during the second half of the night impairs consolidation of learned motor skills (Kalat, 2013). Consolidation represents the processes by which memory becomes stable. To add, after sleep drive has disappeared in the second half of the night, suprachiasmatic nucleus (SCN) can maintain sleep throughout the night (Kalat, 2013). Hormones and Sleep
Researchers of sleep state that there are two different bodily processes that must work together in order to allow a person to fall asleep: the circadian rhythm and the accumulation of hypnogenic substances. “The circadian rhythm controls the cyclical secretion of several hormones, including melatonin, that are involved in sleep” (Walecka-Kapica, 2014). The accumulation of hypnogenic substances induce a desire to sleep that does not disappear until one actually gets sleep. This means that your hormones must be at a certain balance in order to allow for sleep to occur, and it needs to be a certain amount of time since you last slept in order for the substances to rebuild themselves. Cortisol is an anti-stress hormone that increases while the growth hormone decreases when the body gets less sleep than it should. An increase in cortisol can cause memory loss and insulin resistance. A decrease in the growth hormone can reduce muscle mass and strength, increase fat tissue, and weaken the immune system (Walecka-Kapica, 2014). Effects of Sleep Deprivation
Sleep loss is said to be one of the many reasons to disrupt a person’s quality of life. The distinction between total sleep deprivation and partial sleep deprivation is important to understand. Homeostasis and the circadian rhythm are needed in order to have a successful night of sleep, and when these two things are affected by outside forces, it can affect one’s function. One’s sleep-wake cycle can be damaged by outside forces such as stress, anxiety, fear and aggression as mentioned before. Cognitive performance is seen to have declined after chronic sleep deprivation, including one’s memory functions, long term and short term. It is important for everyone to know the effects that sleep deprivation can have on an individual. Conclusion
As mentioned before, sleep is a process that is essential to life. Not only is sleep a process that is essential to one’s overall health, but a lack of it can impact one’s quality of life throughout their waking hours. Although it might seem as if there is not anything that we don’t already know when it comes to medicine, there is in fact a great deal that we do not know. With a process so seemingly simple as sleep, it is hard to overlook the subtle, yet vital support that it provides to the health of the individual.
Kalat, J.W (2013). Biological Psychology (11th ed.). Wakefulness and Sleep. Belmont, CA: Cengage Learning/Wadsworth The central nervous system. (2009). Retrieved from https://aspsychology101.files.wordpress.com/2009/09/4-1-the-central-nervous-system.pdf Walecka-Kapica, E., Klupińska, G., Chojnacki, J., Tomaszewska-Warda, K., Błońska, A., & Chojnacki, C. (2014). The effect of melatonin supplementation on the quality of sleep and weight status in postmenopausal women. Menopausal Review / Przeglad Menopauzalny, 13(6), 334-338. doi:10.5114/pm.2014.47986