Sleep Physiology and Chronobiology: Understanding Sleep Function
a. Global vs Local Aspects of Sleep
Sleep occurs locally but demonstrated globally
We live our entire life in two states, sleep and awake1. These two states are characterized by two distinct behaviors. For instance, the brain demonstrates a well-defined activity during non-REM sleep (nREM) that is different when we are awake. In the study of sleep by Huber et. al., the authors stated that sleep is in fact a global state2. It is unclear whether this statement means that sleep is a state of global behavioural inactivity or the state of the global nervous system. The notion that sleep is a global state of the nervous system served as basis for sleep researchers to search for a sleep switch. The discovery of the sleep switch, in return, provided evidence and enhanced the notion that sleep is a global state of the nervous system. The switch hypothesis developed from the fact that sleep can be initiated without fatigue and it is reversible1. It was hypothesized that there is something in the brain that has the ability to control the whole brain and initiate sleep. Studies have found a good candidate that demonstrated this ability3. They found a group of neurons in the Ventrolateral Preoptic (VLPO) nucleus. It was a good candidate because it was active during sleep, has neuronal output that can influence the wakefulness pathway, and lesion in the area followed reduce sleep3. The idea that there is something that can control the whole brain and result sleep state supports the idea that sleep is a global state of the nervous system.
Recently, however, intracortical recordings of epileptic patients and of mouse brain during sleep found evidence that the brain can have region...
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...ep. There are events in sleep that are associated with synaptic modification, which is the basis of brain rewiring that enhances cognition. There is evidence that sleep accelerated transcription of cortical genes that are associated with protein synthesis9. These newly generated proteins are known to be required for strengthening of existing synapses and building new synapses. Studies have found increase of factors associated with brain-plasticity and enhanced learning during sleep5. These factors include phosphorylated or activated CREB, a transcriptional factor, as well as Arc, BDNF, and NGFI-A. These evidence help explain how sleep can influence brain rewiring through synaptic modification. This mechanism helps explain how sleep can modify the brain and ultimately enhance learning. This is a strong evidence that supports the synaptic downscaling hypothesis.
All mammals exhibit Rapid-Eye-Movement, or REM, sleep, and yet on certain levels this type of sleep would seem to be disadvantageous. During REM sleep, which is when most dreams occur, the brain uses much more energy than during non-REM (NREM) sleep. (1) This "waste" of energy coupled with the increased vulnerability of this state on account of the body's paralysis at this time suggests that there must be a very important reason, or reasons, for the existence of REM sleep and in extension of dreams. Determining the function of dreams, however, has proved very problematic with many arguments which directly oppose each other. Some of the primary functions of dreaming have been tied to is role in development, its production of neuro-proteins, and also to how it may allow for the "rehearsal" of neurons and neuronal pathways. The influence of dreaming on learning is one of the hottest debates. Some argue that dreams aid in learning, others that dreams aid in forgetting, and yet others that dreams have no effect on learning or memory. That REM sleep seems to aid in development might argue that REM sleep may be connected to learning. It seems that most scientists believe that REM sleep aids in certain memory consolidations although some argue that it actually leads to "reverse learning.
Rasch, B., & Born, J. (2008). Reactivation and consolidation of memory during sleep. Current Directions in Psychological Science, 17, 188-192. doi: 10.1111/j.14678721.2008.00572.x
Kales, A. (1972). The evaluation and treatment of sleep disorders : Pharmacological and psychological studies. In M. Chase (ed.)The Sleeping Brain. Los Angeles : Brain Information Service.
In a short story called," Sleep," written by Haruki Murakami and translated by Jay Rubin, is a story about from the perspective of a thirty years old woman who is a respected housewife in the day time and a woman who does things which aren 't routine in her night life. This short story holds many controversial viewpoints of a person 's perspective as they read through to better understand what the main character is going through. The main character goes through a transformation as she suffers from insomnia and tries to understand what the true version of herself is.
The word circadian comes from the Latin circa diem meaning about a day, which starts out as a good definition for circadian rhythms. Circadian rhythms do not have to be daily and in fact can happen in multiple periods per day or periods that last longer than days such as circannual rhythms. The most thought of circadian rhythm is sleep but other examples include, body temperature, blood pressure, production of hormones and digestive secretions. These rhythms do not only take place in humans but are present in a wide variety of other organisms, the simplest being cyanobacteria. Circadian rhythms are usually controlled by a combination environmental factors and internal factors. The most common environmental factors are temperature and light.
Sleeping is something that is an essential part of human nature and is a must in order for one to be a functional human being. Sleep is an idea that is accompanied by many wives’ tales, including the idea that one needs seven to eight hours of sleep each night and alcohol helps one fall asleep and sleep more soundly. One myth about sleep is that during sleep, one is in a state of nothingness. In truth, however, it has been discovered that during sleep the brain is active, variations in heartbeat and breathing occur, and the eyes and ears are active throughout the time of sleep. These activities during a person’s sleep are important because they help that person be more aware, awake, and alert during sleep.
Sleep is a reversible, repetitive, and active behavior which plays different roles. These roles include restoration processes, memory consolidation, learning or growth. As argued out by Curcio, Ferrara and De Gennaro (2006), during sleep, neuro-cognitive, psychological, as well as behavioral processes take place. Many individuals sacrifice their sleep with an aim of carrying out extra activities. However, sleep loss has been found to have various negative effects. Some of these effects include impairment in psychomotor, neurocognitive performances, and sleepiness (Curcio et al., 2006). Results from recent studies have demonstrated that sleep plays an integral role in memory consideration and learning processes (Deregnaucourt et al., 2005 & Curcio et al., 2006). This paper will evaluate journals and other accredited sources of information in an effort to review, analyze, critique and synthesize works of other scholars on how sleep affects learning.
The most popular natural aid for sleep is melatonin. Supplementation with melatonin has been shown in several studies to be very effective in helping to induce and maintain sleep in both children and adults, and in both people with natural sleep habits and those with insomnia. However, the sleep-promoting effects are most apparent if melatonin levels are low. In other words, using melatonin is not like taking a sleeping pill. It has a sedative effect only when melatonin levels are low. When melatonin is taken just before going to bed in normal subjects or in patients with insomnia who have normal melatonin levels it has no sedative effect. This is because there is normally a rise in melatonin secretion just before going to bed. Melatonin supplementation appears to be most effective in treating insomnia in the elderly, in whom low melatonin levels are quite common.
Doctors have been saying for years that you should not stay up late, or not to sleep in during the day. Doing these things can lead to dementia, heart disease, and early death. One part of sleep is actually found to be more important.
Mignot, Emmanuel, Shahrad Taheri, and Seiji Nishino. "Sleeping with the Hypothalamus: Emerging Therapeutic Targets for Sleep Disorders." Nature.com. Nature Publishing Group, n.d. Web. 15 Dec. 2014.
Sleep is a very important factor in the human function. Our body and brain is able to reset itself and rejuvenate while we sleep. When we do not get the required amount of sleep, we start to feel lethargic and foggy minded, because our mind and body wasn’t able to replenish itself. Sleep is imperative that an insignificant rest deficiency or lack of sleep can affect our ability to remember things; decisions and can affect our temperament. Chronic sleep deficiency can get the body to feel agitated and it could lead to serious health problems such as, heart problems, stress, acne, and obesity.
Alzheimer’s disease affects the brain’s intellectual functions due to the memory deteriorating and is the common cause of dementia. Sleep regulation is disrupted and sleep is in fragments during the night with a reduced period of deep REM sleep (Epstein,
Maynard, W., & Brogmus, G. (2006). Safer shift work through more effective scheduling. Occupational health and safety, 16.
Sleep is very important to our body for relaxation, preparing ourselves for the next day. Unfortunately, poor sleeping quality is prevalent in modern cities such as Hong Kong. An increasing number of university students have stated sleep problems. (Suen, Hon & Tam, 2008). Meerlo, Mistlberger, Jacobs, Heller & McGinty (2009) have reported that prolonged sleep loss may affect the rate of neurogenesis...
Rasch, Björn, and Jan Born. "About Sleep 's Role in Memory." Physiological Reviews. American Physiological Society, n.d. Web. 06 May 2016.