Going by a general overview, sleep can be seen as a long period of loss of consciousness but during which one can awakened from. Sleep is a normal state of bodily behavior change where one enters a period of unconsciousness, the sensory and movement activities are deferred and all voluntary muscular movements suspended.
During sleep, a person is less aware of the external environment and the source of stimuli at this stage is primarily internal. A more elaborate look into understanding sleep take a look at the two aspects of sleep which is the behavior observed during sleeping periods as well as the scientific explanation of the physiological processes involved during sleep.
Behavioral perspective looks at sleep as a period characterized by immobility or slight movement, a decrease in eye movements, a decrease in awareness of external stimuli, certain body postures, unconsciousness that is in real sense reversible, and reduced cognition. The physiology of sleep is well understood by looking at the electrical rhythms of human mind recorded during sleep. An understanding of these two aspects of defining sleep helps us to explain the step by step process of sleep (Russo, 2005).
The process of sleep follows 5stages each marked by a difference in brain wave patterns. The stage 1 consists of periods during which one switches between sleep and wakefulness. The amount of sleep here is light making it easier to stay in touch with external stimuli. This is the stage which the muscles enter a relaxation state. Being the first stage, it marks the first few minutes after one falls asleep and since it is light, one can be aroused and awakened from time to time by any slight disturbance. It forms 5-10% of the whole sleep period.
The second stage marks the first feel of the actual sleep during which one looses total consciousness. Movement of the eyelids cease at this stage and the brain waves slowdown. The heart rate also decreases and is accompanied by a fall in body temperatures. This stage accounts for 40-50% of the total sleep period.
Stage 3 is marked by a major slowdown in brain wave movements. This marks the entry into a period of deep sleep during which one cannot easily be awakened. A person awakened at this stage has immediate feels of disorientation and takes sometime to completely adjust to wakefulness.
Stage 4 is hard to differentiate from stage 3 and in some cases the two have been combined. It is the stage where brain waves reach very slow movement patterns. At this stage, much of the blood that goes to the brain is now diverted to the muscles and energy lost during various activities begins to be replenished. This stage marks very intense deep period of sleep. This is the stage during which certain sleep disorders like sleepwalking, bedwetting and nightmares are experienced (Billiard & Kent, 2003)..
The last stage of sleep is known as REM standing for rapid eye movement. This occurs 70-90 minutes from the time one falls asleep and in the total sleep time it makes up 20-25% and occurs for about 4-5 times during the whole sleep period. Most dreams occur at this stage of sleep.
REM periods start as short durations but as sleep cycles progress the duration of REM increases. During this stage, the eyeballs increase in movement, the heart rate and breathing rate increases but occur in irregular at irregular intervals, and blood pressure increases. REM also marks a period during which the muscles are temporarily paralyzed making limbs movement impossible.
This is considered an important phenomenon since if this was not to happen people would be acting according to their dreams at this stage. The brain waves at this stage are actually very fast and high indicating that the brain is very active. The levels of brain activity are almost as high as those experienced when one is awake. It has been found out that if one is awoken during the REM stage, it is possible to remember their dreams very vividly (Hunt, 2009).
The term getting enough sleep does not only refer to being in bed for a long time, it incorporates spending enough amount of time in each of the sleep stages. Each stage of sleep brings with it benefits to the body and therefore sleep as a whole is beneficial. Sleep has been termed as an important period during which restoration of various body resources occur. This is recorded in various areas such as restoration of energy levels.
This occurs mainly in stage 4 when various body processes increase and blood is directed to the muscles thus restoring energy lost during work. Sleep is also important in restoration in from of healing wounds. This is shown by the decreases in white blood cells reported in cases of sleep deprivation.
Related to this is the fact that the immune system is also boosted by getting enough sleep. During the REM stage when the body processes and brain activity are almost as those recorded when one is awake, results in increased metabolism during which the growth hormones are secreted thereby marking the importance of sleep in the growth process.
Sleep has been shown to contribute to learning and memory processing. Adequate sleep assists the brain in processing new information taken in and preserving it in the long term memory which improves the cognitive functions. Various studies have shown that sleeping after taking in new information resulted in higher chances of memorizing the facts afterwards.
Lack of enough sleep also leads to an impaired memory. Getting enough sleep ensures that one gets enough rest to replenish the nervous system. This ensures that a person has the physical ability to face the day ahead.
Getting enough sleep acts as a safety measure that reduces the chances of mishaps. A sleep deprived person may find themselves dozing off during the daytime and during the working hours. This increase the chances of making errors which might result in mistakes that maybe of great consequences such as traffic accidents, tripping and falling, and accidents at work place.
The relaxation effect and restoration that is brought about by getting enough sleep means that the person wakes up when in a good mood. Sleep deprivation on the other hand has been associated with irritability, loss of concentration, lack of patience and general low moods.
Sleep has been linked to cardiovascular health with studies showing that sleep reduces the chances of elevation of the cardiovascular illnesses. The explanation for this is that sleep disorders result in health conditions such as hypertension, stress, and the heart beating unevenly. These factors highly increase the chances of attack by cardiovascular illnesses.
After clear understanding of the importance of sleep in the functioning of a person’s body, it should be understood that the amount of sleep needed for normal functioning is different compared to the amount of sleep that a body requires for optimum functioning capacity. This however differs from person to person with some people recording additional benefits from sleeping for longer while others get maximum benefits for getting just enough sleep.
There is however no definite formula for determining the exact duration needed for each person to know when they get optimum benefits, but one can always try and evaluate how different sleep duration serves to fulfill their sleep needs. Experts such as National Institute of Health have however come up with a conclusion of the average amount of time that persons in different age groups need per night.
During the infant stage of growth, the amount of hours that should be spent on sleep is greater. This sleep duration at this stage occurs in a number of sessions which when added up give the total amount of sleep time in infancy stage. The total sleep time in infancy add up to 14-16 hours per day. The total sleep time the hits a decrease phase as the young baby grows in age. Sleep in infancy stage is different in that a bigger amount of sleep time is spent in REM other than deep sleep. This is the reason the newborns are often switching between wakefulness and sleep. This is important for the rapid growth that takes place in newborns and is facilitated by the REM stage of sleep.
As one enters the adult stage of growth, the average sleep time required per night decreases to 7-8 hours, with different sources quoting varying figures but close to this. The amount of sleep needed however varies with some people requiring less hours and other more than 8 hours of sleep.
The determinant here is whether the individual had in the recent past been deprived of sleep which requires compensation. Spending less than the required time in sleep is detrimental as it leads to ‘sleep debt’. This has been shown to have adverse effect on human mind and body functioning and can only be resolved by sleeping for longer hours. As one reaches old age, sleep tends to be light and the duration spent in sleep is usually shorter.
The shortened duration is as a result of a decrease in the amount time spent on stages III and IV of the sleep time which in average goes down by approximately 10-15%. Although there has been reported an increase in time spent in stage II amongst the old, the increase is low and not enough to compensate for the time that is lost in stage III and IV. Old people experience difficulties in falling asleep coupled with periods of arousals during sleep which marks the shortening of the total sleep time.
This can only be compensated by increasing the amount of time spent in bed or otherwise cases of loss of sleep are reported. These cases are compounded by the various medical conditions that are associated with aging like breathing difficulties during sleep, weakened muscles, and weakened heart function (Smith & Segal, 2010).
Getting enough sleep is very essential for optimum functioning of both the human mind and the body. A person who doesn’t spend the required amount of sleep time per night is termed as being sleep deprived. While the indicators of sleep deprivation may not be so intense as to be figured outright, the compounded effect that it has on a person’s lifestyle is one that can affect the total body output until the problem is resolved by compensating fro the lost sleep.
Sleep deprivation can be caused by several factors which include; sleeping late which means reduced total sleep time, waking up earlier than accustomed for, interruption during sleep which means that certain stages of sleep are interrupted, or failing to sleep completely (Milner & Cote, 2008).
Sleep deprivation is shown by signs that in most cases are considered to be normal. One should be able to wake up naturally after spending enough time sleeping, however most people need alarm clocks to act as reminders which is a clear sign of sleep deprivation. If you struggle to get out of bed when it’s time to wake up, you are possibly sleep deprived. Simple laziness that is synonymous with afternoon sessions, or feeling sleepy in odd places and times like in meetings or classroom marks the evidence of sleep deprivation.
After heavy meals and especially in the afternoons, most people consider taking a nap as a normal routine while in the contrary it shows signs of a sleep deprived individual. Another sign of a sleep deprived person is dozing off while in a vehicle, or watching TV as well as falling into deep sleep immediately after getting to bed.
Sleep deprivation results in general reduction in functional capability of a person. This emanates from the various effects that are resultant from sleep deprivation. A sleep deprived individual lacks motivation and shows general sluggishness as well as low concentration levels.
Lack of enough sleep causes one to be moody and easily angered which in sense leads to an increase in stress levels and inability to make sound decisions and solve problems. Health wise, sleep deficiency weakens the body immune system resulting in frequent attacks by diseases such as colds. One’s safety is put at risk as the impairment in motor skills can result in fatal accidents. Sleep deficiency has been associated with cases of weight gain, diabetes and cardiovascular illnesses.
Normal sleeping is sometimes interrupted resulting in what we term as sleeping disorders. The various disorders associated with sleep occur in various manners; disruptions during sleep, difficulty sleeping in general, and sleeping for longer durations. The most evident and probably the most commonly known disorder of sleep is insomnia. The disorder is characterized by general lack of sleep during the night.
It occurs when one is unable to initially fall asleep and maintain continuous sleep durations. It is also reported in other cases as awakening in early morning hours and failure to fall asleep after sleep is interrupted. The diagnostic criteria for insomnia require that the incidents of lack of sleep occur for 3-4 times in a week and continue for a period exceeding one month. Insomnia can be either acute or chronic.
The acute type is not persistent for long and is said to result from stressful conditions and disappears soon after the situation normalizes. Chronic insomnia however is the most common and is often coupled by other conditions such as mental disorders, medication, as well as drug abuse (Lee, 2006).
Another sleep disorder that is common today is sleep apnoea. It occurs in two different ways and can therefore be classified as either Obstructive sleep apnoea syndrome (OSAS) or central sleep apnoea (CSA). Obstructive sleep apnoea syndrome is characterized by partial blockage of the airway which results in difficult when breathing during sleep.
Some of the common cases of OSAS are when sleep is accompanied by heavy snoring, a feeling of chocking, instances of complete absence of breathing, and physical movements such as jerking and trembling indicating that the airway has been obstructed. It consequently affects the sleep patterns and those who suffer the condition often fail to enter the deep sleep stages of sleep.
According to Chowdhuri & Badr (2008), Central Sleep Apnoea on the other hand occurs when there is failure in breathing during sleep brought about by the inability to control the ventilatory motor output which normally is responsible fro opening up the airway during breathing. CSA brings about symptoms similar to those of insomniacs coupled with feeling sleepy during the day and awakening during sleep hours.
Narcolepsy-cataplexy is a sleep disorder that is marked by frequent sleep attacks especially during the daytime hours. This is often frequent and persists for quite sometime and therefore should not be mistaken from the daytime sleepiness that is as a result of insomnia, interrupted sleep during the previous day, boredom, or due to physical fatigue. The frequent attacks of sleep occur are rapid and one is unable to control falling asleep.
It happens for a short duration ranging from seconds to several minutes. A good number of people have been said to suffer from narcolepsy and are aware of the symptoms but most of those who suffer it never seek medical interventions and hence continue to live with the problem. The sudden attacks of sleep can in other cases be coupled with a feeling of weak muscles that are unable to support the body, a condition known as cataplexy.
When the two sates combine to result in a condition that is referred to as Narcolepsy-cataplexy, the result is an incidence of a total body muscular collapse coupled with some deep sleep lasting for a few minutes and could be confused with epilepsy. The common cause of the condition is said to be a malfunction in the central nervous system which can be kept in control by persistent use of medication (Chou & Chuang, 2008).
A number of sleep related abnormal behaviors have been related to a sleep disorder known as parasomnia. Parasomnia is a condition associated movements and actions that are unusual during sleep and periods during which one is aroused from sleep either leading to disruption of sleep or not.
Several disorders of sleep are categorized under parasomnia. The most common of these is sleepwalking. It is a disorder that is common amongst the children of up to 12 years. Its start is marked by activation of the motor activity when the brain enters a slow wave phase.
This is followed by several minutes of abnormal movement around the room or house. There have not been any reported cases of criminal activities that have taken place as a result of sleepwalking. Causes that are said to bring about this condition are lack of enough sleep, exhaustion, prevailing ailment, and certain sedative drugs. Another parasomnia disorder is night terrors. This condition is marked by the person making sharp intense screams in their sleep that are usually combined with a feeling of fear and confusion.
Nightmares are said to occur during the phases of slow brain wave movements too. In most cases, patients who are diagnosed with night terrors also experience sleepwalking disorder. Factors said to contribute to night terrors are sleep deprivation, loss of energy, illness, drugs that give a hypnotic feeling, and related incidents (Synder, 1987).
Another parasomnia related disorder is Rapid Eye Movement sleep disorder (RBD). A person expiring RBD often does action that mimic the dreams they are having usually in the 5th stage of sleep which is the Rapid Eye Movement phase. The abnormal dream actions often end up in injuries to the person or the bed partner.
This disorder is mostly experienced amongst the aged population. For this reason a link was discovered that associated the process of neurodegenerative diseases amongst the aged with the occurrence of RBD. Bruxism is a sleep disorder that categorized under the parasomnia disorders of sleep.
It is marked by abnormal tooth grinding during sleep. It is common during the adolescent years but cases have been reported of old people with the condition. Bruxism has been associated to prevalence of certain disorders amongst the children e.g. cerebral palsy. Factors that elevate the tooth grinding for person’s suffering from bruxism are apprehension, tension, stress, and dental related diseases (Chokroverty, 2009).
In conclusion, sleep has been a much researched on subject with helpful information being substantiated. This include the process of falling asleep and the importance of each stage, the importance of sleep in mind and body function, and the various disorders that are associated with sleep.
People can now be able to make good timing of their sleep hours and get the average amount of sleep time needed for healthy functioning. Sleep has therefore proven an important subject that requires understanding by every person who wants to avoid the common assumptions and seeks to get good sleep for it has been found out that sleep influences every aspect of mind and body function.
References
Billiard, M. & Kent, A. (2003). Sleep: Physiology, Investigations, and Medicine. New York: Springer.
Chowdhuri, S. & Badr, M. S. (2008). Central Sleep Apnoea. Indian Journal of Medical Research ,131(6). 150-164.
Chokroverty, S. (2009). Overview of Sleep & Sleep Disorders. Indian Journal of Medical Research, 131(5), 126-140.
Chou, Y. & Chuang, L. (2008). Hyperlipidaemia in Patients with Sleep-related Breathing Disorders: Prevalence and Risk Factors. Indian Journal of Medical Research 131(7), 121-125.
Hunt, B. (2009). Stages of Sleep. Dream Views, 23(12), 11-17.
Lee-Chiong, T. (2006). Sleep: A Comprehensive Handbook. Hoboken, NJ: John Wiley and Sons.
Milner, C. & Cote, K. (2008). Benefits of Napping. European Sleep Research Society Journal, 18(9), 272-281.
Russo, M. (2005). Sleep: Understanding the Basics. e-Medicine Health Journal, 120. Web.
Smith, M. & Segal, R. (2010). How Much Sleep do you Ned? Guide to Healthy Sleep, 12(5), 36.
Synder, G. (1987). Sleep Disorders. Professional Sleep Societies Journal, 13(4), 3-6.