Functions and brain mechanisms of sleep

Sleep, it's the state in which we spend a lot of our lives yet so little is known about it. It has long fascinated psychologists and many have searched for to unravel its mysteries. Yet like all the behaviours sleeping can be examined using the same natural, subconscious and environmental methods that are so effective in the areas. Defined, sleep is a normally recurring condition which is characterized by reduced or absent consciousness, relatively suspended sensory activity, and inactivity of almost all voluntary muscles. However this talks about what is noticeable, through the years theorists tried out to explain what's happening biologically during sleep.

Up until the 1950's researchers assumed that sleep happened due for an overtaxing of the brain, that the regular sensory stimulation that bombards the mind during the day renders it struggling to maintain a waking level of brain activity. They also believed that reaching this state was helped by the occurrence of the darkness and silence of night time. Sleep at this time was also viewed as a homogeneous status and consequently of the many researchers viewed it as relatively uninteresting. This may be a reason why very little methodical attention was put on this issue for such a long time. In fact desire interpretation garnered far more attention at this time (Dement, 1998). This "passive process theory" was only fell when experimenters documented eye activity and muscle tension during sleep. This led to the groundbreaking discovery that there have been in fact two different classes of rest, rapid eye movements (REM) and non-rapid eyes movement sleep(NREM) (Watson, Breedlove & Rosenweig, 2010).

In this essay rest, both rapid-eye movements and slow-wave, will be explored. Also set out will be the primary functions of sleep and what can happen whenever a person is deprived of sleeping. Finally the sleeping disorder narcolepsy will be reviewed as it can be an often misunderstood disorder which ultimately shows the mal results when control over when to rest is lost.

Sleep can be divided into 5 phases, 4 of the stages are during NREM with the ultimate level being REM sleep. These periods are measurable by the habits of electrical power activity in the brain. When awake the brain shows habits of "beta waves". These have a higher occurrence and low amplitude. When in a state of relaxation the mind shows waves with lower frequencies, they are called "alpha waves" (Passer & Smith, 2009)

Stage 1 of NREM occurs just as your body drifts into rest. At this time the brain starts to demonstrate "theta waves". These waves are slower again than those measured during a drowsy state and have unusual frequencies, the heart rate also slows and muscle anxiety is reduced. This stage normally will last several minutes, offering way to stage 2. Here the mind shows brief (1-2 seconds) periodic bursts of brain activity. These bursts are called sleeping spindles. Interesting to note is the fact that often people deny that these were even asleep if they are awakened during either the first or second stage. As your body drifts even more deeply into slumber stage 3 is reached, here "delta waves" will be the most dominant. These are of an extremely low frequency and also have large amplitude. Stage 4 is nearly the same as level 3 and shows further minimizing of consistency and extension of amplitude. Stages 3 and 4 are also sometimes known as slow-wave sleeping (SWS) by some research workers. After reaching this stage your body then cycles through the previous periods and generally after 60-70 minutes of drifting off to sleep the body has gone through a circuit of phases 1-2-3-4-3-2. It is at this point that brain activity changes alarmingly and a whole new and unique stage of sleep emerges. This new level is called rapid-eye activity (REM) rest (Watson et al, 2010).

This stage of rest was uncovered by Aserinky and Klietman in 1952 which is characterised by high brain arousal, swift eye motion and frequent vivid dreaming. These researchers found that in this stage the sleeper revealed bursts of muscular action which led to the persons eye moving rapidly underneath the eyeball lid, this happened around every minute during REM sleep. People that were awakened during this stage frequently survey having a goal, this is even true of men and women who before said to acquire "never imagined" (Passer & Smith, 2009). Brain activity heightens to daytime levels and the body also becomes physiologically aroused, with an increase of rapid breathing and a swifter heartbeat. Another attribute of this level of sleep would be that the bodies of both men and women become aroused, regardless of aspiration content, with penile erections in men and genital lubrication in women. The mind also can send alerts to the muscles of the forearms lower limbs and torso which will make them become very relaxed, they occasionally twitch but movement is not possible at this time. This is sometimes known as "sleep paralysis".

After an average of 90 minutes the body begins the routine of stages anew, however with each recurrence REM sleep lasts longer, eating into the time previously put in in level 3 (Passer & Smith, 2009).

The brain manages the passage of your body through sleep however no single part from it is solely accountable for it. Various mechanisms in the mind control the different areas of the sleeping body, areas on the base of the forebrain are connected with the work of falling asleep. Other parts in the mind active while asleep are certain areas in the mind stem which regulates REM sleep. Here neurons are comprised which switch on the other brain systems that happen to be needed during REM such as those for the rapid-eye activity and muscular paralysis. Thoughts are reached during REM rest and this is also governed by these areas in the brain stem. This influences what's experienced during dreams(Watson et al, 2010).

Having explored the biology behind sleep it is currently worth considering the benefits associated with sleeping, both physiological and subconscious. A couple of two major branches of thinking which explore the question of why do we rest? These are the repair models and the evolutionary/circadian models (Passer & Smith, 2009).

According to the evolutionary models rest recharges run-down systems, it we can get over physical and mental fatigue. That is largely reinforced by research in rest deprivation. Among one of these studies is the planet record look at by Randy Gardener in 1964. He remained awake for 11 days as part of a school science fair task and he allowed rest researchers to study him during this period. Over the first few days he was irritable, forgetful and nauseous, by the fifth day he commenced to experience intervals of disorientation and possessed slight hallucinations and by the finish he experienced slurred conversation and finger tremors (Gulevich, Dement & Johnson, 1966). This research obviously shows physiological and mental problems that arise from sleep deprivation. However it has been proven that less sleep is necessary as you age with older people living healthy lives on only 5 or 6 hours sleep. Actually there is one of these of your 70 season old female who could make it through on 1 hour of rest a night. Many researchers also think that a cellular waste products chemical substance called adenosine has a role in the restorative functions of rest. Adenosine is produced as skin cells produce energy. At high levels adenosine inhibits brain operation and levels of it reduce during deep sleeping (Passer & Smith, 2009).

Evolutionary/Circadian models declare that the primary function of rest is prolonging a types survival in accordance with its environmental needs. It backs up its data based on the fact that prehistorically our ancestors acquired very little to find by being dynamic at night as food gathering etc was a lot more easily achieved in the day. The model places forward the idea that during the period of the evolution of a varieties a "circadian sleep" is developed. This is a wake design that becomes heredity scheduled to certain factors such as its position in the predator victim relationship and its food requirements. Also researchers backing this model believe sleep also advanced as a way of conserving energy, placing forward the actual fact that we consume to 25% less energy when asleep (Watson et al, 2010).

A controversial theory on the benefit of sleeping is one that links it to recollection consolidation. The purpose of REM rest remains unknown plus some have submit the idea that it is a tool that the mind uses to consolidate memory, a process in which the brain transfers information to the permanent ram. This consolidation hypothesis is however contradicted by the actual fact that studies also show that even when a person has little if any REM sleep credited to a side-effect of anti-depressant drugs they show no impairment of permanent memory capacity. This has led some to state that REM sleeping is necessary over a purely natural level. These theorists assume that the body uses REM sleeping primarily to keep carefully the brain from very long periods of low arousal as they imagine this could have damaging results. The true purpose of REM sleep continues to be debated (Watson et al, 2010).

An interesting analysis by Paller and Voss provided evidence that suggests that when remembrances are accessed during dreaming they could be subtly altered by the goal. This has is to do with recollection consolidation. There review showed that the brain does indeed use dreams, at least on a small scale, to assist in ram consolidation as has been recently known. However that the brain can alter these dreams is interesting to say the least (Paller & Voss, 2004).

Whereas it's been discussed how too little rest can impair your body, here, the rest disorder narcolepsy will be explored, demonstrating how a failure to stay awake can also cause problems to a person's lifestyle. About 1 from every 2000 people have problems with narcolepsy, those living with the disorder have to deal with daily rounds of sleepiness and uncontrollable sleep episodes where they can go into sudden sleep for less than one minute to a whole hour. Often these sleep disorders are combined with sleeping paralysis or hypnagoic hallucinations. Some experts believe narcolepsy is a disorder relating an intrusion by REM sleeping into waking life. It really is assumed that narcolepsy is cause because of a chemical substance imbalance in the hypothalamus. There is no cure but some ant-depressant drugs seem to be effective in minimizing episodes, this may be due to their suppression of REM sleep.

In conclusion, research around rest has come quite a distance since its humble beginnings. We have now know far more about the biology behind sleeping and yet much of it, including REM sleep still confounds many analysts.

This essay has also outlined the countless benefits that rest has, both physiological and subconscious and shows the difficulties that happen from a lack of it and has shed some light on the obscure and misunderstood sleep disorder narcolepsy. It really is hoped that research will keep on in the future and maybe the mysteries surrounding the state which we spend almost one third of your life in will be unravelled.

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