Sleep – Stages, Theories & Sleep disorder

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Sleep – Stages, Theories & Sleep disorder

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Sleep – Stages, Theories & Problems with Sleep :

Sleep – Stages, Theories & Problems with Sleep By Col Mukteshwar Prasad( Retd )

Sleep – Stages, Theories & Problems with Sleep :

Sleep – Stages, Theories & Problems with Sleep Understanding the sleep process as well and why we sleep is a topic of interest for many including those who have spent a restless night tossing and turning. Stages of Sleep: Sleep is not a fairly uniform process but progresses through a number of different stages that are marked by distinctive changes in brain activity Why We Sleep: While there are a several different theories to explain why we sleep, scientists are still do not have a hard and fast answer for exactly why we sleep. One of the major theories suggests sleep is important for repair and restoration of the mind and body Problems with Sleep: Sleep disorders are a relatively common problem. Severe problems with sleep have even been linked to major depression and even suicide.

Stages of Sleep:

Stages of Sleep During the 1950s, a gradate student named Eugene Aserinsky used electroen cephalograph to discover what is known today as REM sleep. Further studies have demonstrated that sleep progresses through a series of stages in which different brain wave patterns are displayed. There are two main types of sleep : Non-Rapid Eye Movement (NREM) Sleep (also known as quiet sleep Rapid Eye Movement (REM) Sleep (also known as active sleep or paradoxical sleep The Beginnings of Sleep During the earliest phases of sleep, you are still relatively awake and alert. The brain produces what are known as beta waves, which are small and fast. As the brain begins to relax and slow down, slower alpha waves are produced. During this time when you are not quite asleep, you may experience strange and extremely vivid sensations known as hypnagogic hallucinations. Common examples of this phenomenon include feeling like you are falling or hearing someone call your name. Another very common event during this period is known as a myoclonic jerk. If you've ever startled suddenly for seemingly no reason at all, then you have experienced this odd phenomenon. While it may seem unusual, these myoclonic jerks are actually quite common .

Stages of Sleep…:

Stages of Sleep… Stage 1 Stage 1 is the beginning of the sleep cycle, and is a relatively light stage of sleep. Stage 1 can be considered a transition period between wakefulness and sleep. In Stage 1, the brain produces high amplitude theta waves , which are very slow brain waves. This period of sleep lasts only a brief time (around 5-10 minutes). If you awaken someone during this stage, they might report that they weren't really asleep. Stage 2 Stage 2 is the second stage of sleep and lasts for approximately 20 minutes. The brain begins to produce bursts of rapid, rhythmic brain wave activity known as sleep spindles . Body temperature starts to decrease and heart rate begins to slow. Stage 3 Deep, slow brain waves known as delta waves begin to emerge during stage 3 sleep. Stage 3 is a transitional period between light sleep and a very deep sleep.

Stages of Sleep…:

Stages of Sleep… Stage 4 Stage 4 is sometimes referred to as delta sleep because of the slow brain waves known as delta waves that occur during this time. Stage 4 is a deep sleep that lasts for approximately 30 minutes. Bed-wetting and sleepwalking are most likely to occur at the end of stage 4 sleep. Stage 5 Most dreaming occurs during the fifth stage of sleep, known as rapid eye movement (REM) sleep. REM sleep is characterized by eye movement, increased respiration rate and increased brain activity. REM sleep is also referred to as paradoxical sleep because while the brain and other body systems become more active, muscles become more relaxed. Dreaming occurs due because of increased brain activity, but voluntary muscles become paralyzed.

Stages of Sleep…:

Stages of Sleep… The Sequence of Sleep Stages However, that sleep does not progress through these stages in sequence. Sleep begins in stage 1 and progresses into stages 2, 3 and 4. After stage 4 sleep, stage 3 and then stage 2 sleep are repeated before entering REM sleep. Once REM sleep is over, the body usually returns to stage 2 sleep. Sleep cycles through these stages approximately four or five times throughout the night. On average, we enter the REM stage approximately 90 minutes after falling asleep. The first cycle of REM sleep might last only a short amount of time, but each cycle becomes longer. REM sleep can last up to an hour as sleep progresses.

Theories of Sleep :

Theories of Sleep A number of different theories have been proposed to explain the necessity of sleep as well as the functions and purposes of sleep. The following are three of the major theories that have emerged: 1.Repair and Restoration Theory of Sleep: Sleeping is essential for revitalizing and restoring the physiological processes that keep the body and mind healthy and properly functioning . This theory suggests that NREM sleep is important for restoring physiological functions, while REM sleep is essential in restoring mental functions. Support for this theory is provided by research that shows periods of REM sleep increase following periods of sleep deprivation and strenuous physical activity. During sleep, the body also increases its rate of cell division and protein synthesis, further suggesting that repair and restoration occurs during sleeping periods. Recently, researchers have uncovered that sleep allows the brain to perform "housekeeping" duties. In an October 2013 issue of the journal Science , researchers published the results of a study indicating that the brain utilizes sleep to flush out waste toxins. This waste removal system, they suggest, is one of the major reasons why we sleep. "The restorative function of sleep may be a consequence of the enhanced removal of potentially neurotoxic waste products that accumulate in the awake central nervous system," the study's authors explain. Earlier research had uncovered the glymphatic system, which carries waste materials out of the brain. According to Dr. Maiken Nedergaard , the brain's limited resources force it to choose between two different functional states: awake and alert or asleep and cleaning up. They also suggest that problems with cleaning out this brain waste might play a role in a number of brain disorders such as Alzheimer's disease. Evolutionary Theory of Sleep: Evolutionary theory, also known as the adaptive theory of sleep, suggests that periods of activity and inactivity evolved as a means of conserving energy. According to this theory, all species have adapted to sleep during periods of time when wakefulness would be the most hazardous. Support for this theory comes from comparative research of different animal species. Animals that have few natural predators, such as bears and lions, often sleep between 12 to 15 hours each day. On the other hand, animals that have many natural predators have only short periods of sleep, usually getting no more than 4 or 5 hours of sleep each day. Information Consolidation Theory of Sleep: The information consolidation theory of sleep is based on cognitive research and suggests that people sleep in order to process information that has been acquired during the day. In addition to processing information from the day prior, this theory also argues that sleep allows the brain to prepare for the day to come. Some research also suggests that sleep helps cement the things we have learned during the day into long-term memory . Support for this idea stems from a number of sleep deprivation studies demonstrating that a lack of sleep has a serious impact on the ability to recall and remember information. Final Thoughts: While there is research and evidence to support each of these theories of sleep, there is still no clear-cut support for any one theory. It is also possible that each of these theories can be used to explain why we sleep. Sleeping impacts many physiological processes, so it is very possible that sleep occurs for many reasons and purposes.

Theories of Sleep… :

Theories of Sleep… 1.Repair and Restoration Theory of Sleep:…. Earlier research had uncovered the glymphatic system, which carries waste materials out of the brain. According to Dr. Maiken Nedergaard , the brain's limited resources force it to choose between two different functional states: awake and alert or asleep and cleaning up. They also suggest that problems with cleaning out this brain waste might play a role in a number of brain disorders such as Alzheimer's disease. 2.Evolutionary Theory of Sleep: Also known as the adaptive theory of sleep, suggests that periods of activity and inactivity evolved as a means of conserving energy. According to this theory, all species have adapted to sleep during periods of time when wakefulness would be the most hazardous. Comparative research of different animal species support this theory. Animals that have few natural predators, such as bears and lions, often sleep between 12 to 15 hours each day. On the other hand, animals that have many natural predators have only short periods of sleep, usually getting no more than 4 or 5 hours of sleep each day.

Theories of Sleep… :

Theories of Sleep… 3.Information Consolidation Theory of Sleep: It is based on cognitive research and suggests that people sleep in order to process information that has been acquired during the day. In addition to processing information from the day prior, this theory also argues that sleep allows the brain to prepare for the day to come. Some research also suggests that sleep helps cement the things we have learned during the day into long-term memory . Support for this idea stems from a number of sleep deprivation studies demonstrating that a lack of sleep has a serious impact on the ability to recall and remember information. Final Thoughts: There is still no clear-cut support for any one theory. It is also possible that each of these theories can be used to explain why we sleep. Sleeping impacts many physiological processes, so it is very possible that sleep occurs for many reasons and purposes.

Sleep Disorders :

Sleep Disorders According to the American Psychiatric Association, sleep disorders are major disturbances of normal sleep patterns that lead to distress and disrupt functioning during the day. Not only are sleep disorders extremely common, affecting virtually everyone at some point in their lives, but they can also lead to serious stress and other health consequences. According to a major survey by the National Sleep Foundation , more than half of Americans reported experiencing at least one symptoms of insomnia several times a week during the previous year. Highlighting another major danger of sleep disorders, the survey also reported that 60 percent of respondents had driven while drowsy during the previous year. 1.Insomnia: Insomnia is most common sleep disorder, affecting nearly 60 percent of U.S. adults at least one night each week. Common symptoms of insomnia include difficulty getting to sleep and waking before it is time to get up. There are many factors that can contribute to insomnia including stress and underlying medical conditions. Typical treatments include sleeping pills and behavior therapy. Practicing good sleep habits can be effective for treating mild cases of insomnia.

Sleep Disorders… :

Sleep Disorders… 2.Sleep Apnea: Sleep apnea is the second most common sleep disorder and affects 20 million Americans. This disorder causes people to stop breathing abruptly while they are asleep. During this brief period, carbon dioxide builds up in the blood and the sleeper wakes suddenly to gasp for breath. The length of time that the sleeper stop breathing can vary from a few seconds to so long that the individuals skin actually turns blue from oxygen deprivation. 3.Narcolepsy: Narcolepsy is a neurological sleep disorder that leads to periods of intense sleepiness during the daytime. People suffering from narcolepsy often experience bouts of overwhelming sleepiness and may fall asleep for brief periods of time during the day. These sleeping periods may last from a few seconds to several minutes and in some cases may last up to an hour or more. Those with narcolepsy can fall asleep in the middle of a conversation, during a meal or even while driving a vehicle.

Sleep Disorders… :

Sleep Disorders… 3.Narcolepsy:… Narcolepsy is a chronic condition that typically begins during adolescence. In addition to sleepiness, narcolepsy is frequently accompanied by cataplexy, which involves a sudden loss of muscle tone and control that can last seconds or minutes. Other symptoms include hallucinations and paralysis during sleep. 4.Sleepwalking & Night Terrors: While insomnia and sleep apnea are more common in adults, other sleep disorders such as sleepwalking and night terrors are far more common in young children. Sleepwalking, also known as somnambulism, is characterized by periods of getting out of bed while asleep. Night terrors are most frequently seen in very young children (between the ages of 2 and 6), but people of any age can be affected by this sleep disorder. Typical symptoms include excessive sweating, shaking and obvious fear .

Top Reasons to Get a Good Night's Sleep :

Top Reasons to Get a Good Night's Sleep How Sleep Improves Memory, Reduces Stress and Enhances Decision-Making Drifting off to sleep in the middle of a long class lecture or meeting or feeling very sleepy or even falling asleep at work are linked lack of sleep to a wide range of ailments, including memory problems and obesity. Sleep May Help You Learn More Effectively Svein Halvor Halvorsen Researchers have long believed that sleep plays an important role in memory, but recent evidence suggests that getting a good night's sleep can improve learning. In one study, researchers found that depriving students of sleep after learning a new skill significantly decreased memory of that skill up to three days later ( Winerman , 2006). Known as the memory consolidation theory of sleep , this notion proposes that sleep serves to process and retain information learned earlier while awake. While there is research both for and against the theory, many studies have shown that sleep can play an important role in certain types of memory.

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