"Blessed are the merciful, for they shall obtain mercy."
"Blessed are the merciful, for they shall obtain mercy."
Nobody is certain why people need to sleep, but many experts believe it is the body’s time to rest and repair itself. During sleep muscle tissue is rebuilt and restored. Just like a car or boat, the body can not go on and on forever without a tune-up or oil change. If the car is not tuned properly, it may still function, but not to its fullest. The body is the same way. People may be able to function without a full nights rest, but at the same time they may not be able to think and perform to the fullest of their potential. Sleep assures that people will be able to operate correctly and in peak performance the next day.
New experiments by NIMH grantee Alan Hobson, M.D., Robert Stockgold, Ph.D., and colleagues at Harvard University have found that the brain also uses a night’s sleep to consolidate the memories of habits, actions, and skills learned during the day. Getting an adequate amount of sleep allows for proper storage of information that has been attained throughout the day.
The sleep-wake cycle is of the most basic of human’s behavioral cycles. Sleep is the anchor in the 24-hour day around which other bodily rhythms are synchronized. The synchronization is created by the natural light-dark cycle generated by the rotation of the earth around the sun. The biological clock of people relies on light input to tell it what time of day it is. The light info is sent to the pineal gland which releases the hormone Melatonin. Melatonin works as a transducer that converts light into information about the time of day. When too little natural light gets into the brain it disrupts the timing of one’s internal clock which in turn may cause one’s sleep-wake synchronization to have a rhythm that is off.
As a result of this synchronization problem, one may find it harder to maintain a normal sleep period. This may result because of shift changes at work or mood disorders such a depression or seasonal affective disorder.
Going to bed at the same time every night, and waking up at the same time every morning, is also very important for keeping one’s internal clock at a normal rhythm. By doing this, people can maintain a normal sleep schedule that allows for optimum sleep performance.
The changes in sleep are measured with an electroencephalograph (EEG), which is a brain-wave machine. During the night the brain gives off small electrical signals that may be recorded on an EEG. While one is awake the EEG indicates small and fast beta waves. Right before sleep the EEG shows patterns of larger and slower waves known as alpha.
There are two main states of sleep – NREM (non-rapid eye movement) and REM (rapid eye movement). NREM sleep is a time when the body and brain relax, and the brain waves are associated with deep waves of inactivity. NREM sleep accounts for an average of about 70% of the total sleep time of a young adult (++++Silentpartners.org++++). There are four main stages to NREM sleep.
In stage one the person becomes less aware of their surroundings. A whisper or a quiet noise may awaken them. Because the person is starting to relax, the breathing becomes slower and more regular. There may also be hypnogogic experiences, where one may undergo dream-like sensations of falling, hearing voices, or seeing flashes of pictures. In stage one the EEG is composed of small, irregular waves that still may show alpha waves are present.
During stage two people become even less aware of their surroundings and their body temperature drops more. Sleep spindles, or short bursts of activity, become present on EEGs during the second stage of sleep.
The third stage marks an even deeper sleep than before. In this stage brain activity starts to show signs of delta waves, which are longer and slower. As the person is in a very relaxed state, they have a slow, regular heartbeat and respiratory rate. Their muscles are very relaxed as well. If a person is awakened in this stage they are confused and react slowly. It is also much easier for a person to go back to sleep that is in stage three.
Deep sleep is finally reached during stage four. During this time, the growth hormone is secreted. This hormone encourages growth in children. In adults it helps with the healing of muscles. This is where the body caries out most of its repair work. The brain is now producing almost pure delta waves as the body is now in the most relaxed state. After some time in stage four, people then slowly work back to stages three, and then two. People will normally shift between these stages about three to four times a night.
During REM the person begins to dream and their eyes move in a rapid, flickering motion while their eyelids remain closed and the brain returns to light sleep. Some of the eye movements correspond to dream activities; however, people that were born blind still experience REM, suggesting that it is a natural part of sleep.
REM sleep is a time where the heart beats irregularly, and blood pressure and breathing dither. Despite all the emotional activity that is going on during REM, one’s body becomes quite still, as if paralyzed. REM-sleep paralysis prevents some dangerous and strange nighttime events. When REM paralysis fails, however, some people will thrash about violently, leap out of bed, and at times attack their bed partners. This is known as REM behavior disorder.
As people grow older, they tend to acquire less sleep than those of a younger age. Infants average in around 16-17 hours per day of sleep. Infants will sleep for three to four hours and the will be up for one to two hours. 50-60% of their total sleep is experienced in REM. After approximately three months a baby’s EEG becomes similar to that of an adult. They start to sleep more during the night and their primary sleep stage changes from REM to NREM.
Toddlers usually nap once a day. At around 2 years of age, most children usually sleep ten hours per day. This sleeping schedule last until the child reaches puberty.
Adolescents tend to go to bed later, sleep the same nine or ten hours as children, and awaken at a later time. During a normal school weak this starts to make adolescents more tired because their biological clock wants them to get up a few hours later than their alarm clock does. This sleep schedule gets interrupted yet again during the weekends, as they tend to sleep longer periods of time. Then when Monday rolls around and it is time for more school adolescents find their biological clock telling them that they should be sleeping longer yet again.
Adults can range anywhere from four to eleven hours of sleep a night, however, the average adult sleeps eight hours a night. The amount of sleep remains pretty constant, but the type of sleep undergoes changes. Adults start to experience more awakenings during the nights and have a harder time falling back to sleep. A forty-year-old person gets half the NREM sleep that a twenty-year-old may get. The amount of REM sleep also decreases as age increases.
As a result of the decrease of REM sleep, it is no surprise that seniors experience the least amount of REM. Seniors average approximately six hours of sleep a night. The also tend to go to bed earlier and wake up earlier. They also experience more awakenings than any other age group at night.
Many people from different cultures take naps every day between one and four in the afternoon. Studies indicate that the human body is inclined to rest in the afternoon in addition to at night. In the afternoon a smaller drop in body temperature and alertness occurs, much like at night. Perhaps this explains why more accidents occur between two and four than at any other time during the day. (+++++art1_qual.cfm++++++).
Recordings of brain and ocular electrical activity monitored while napping revealed that longer one-hour naps contained more than four times as much NREM and REM sleep than the half-hour naps.
Sleep deprivation results in reduced productivity. Losing the ability to concentrate, remember, handle complex tasks, and think logically are all a result of sleep loss. Stress is another problem that may occur with lack of sleep. People that are deprived of sleep have higher levels of stress, anxiety, depression, and may take unnecessary risks.
In a study published in the British journal Occupational and Environmental Medicine, researchers in Australia and New Zealand report that sleep deprivation can have some of the same hazardous effects as being drunk. Getting less than 6 hours a night can affect coordination, reaction time and judgment, they said, posing a very serious risk (+++++cnner++++++++).
Loss of sleep can also result in very dangerous driving. The study found that people who drive after being awake for 17 to 19 hours perform worse than others with a blood alcohol level of .05 percent, the legal driving limit for countries in most western European countries. Although the United States sets their limits at .08 and .1 percent, this is still a very unsafe situation for the drivers and others on the road.
The most common of all sleep disorders is insomnia. People who experience insomnia have difficulty falling asleep. The sleep loss caused by insomnia results in less productivity and increased accidents. It is most common to experience insomnia during times of high levels of stress, although this may not be the only reason for it. Insomnia may usually be cured by taking sleeping pills under the guidance of a qualified physician. It has also been shown that melatonin may also help with getting rid of insomnia in older people that may be melatonin deficient.
Narcolepsy is a sleep disorder where one will suddenly become drowsy and sleepy at unexpected times. These sleep attacks may last anywhere from minutes to hours and can happen more than once a day. There is no known cure and there is no complete treatment for narcolepsy as of now. Evidence suggests that narcolepsy may be inherited from parents to children. There is a one-in-twenty chance of first generation offspring being affected with narcolepsy (Sleep Clinic). The most common treatments for narcoleptics are stimulants that block sleepiness and suppressants that block cataplexy.
Sleep apnea is when the muscles of the tongue and soft palate at the base of the throat allow the breathing passage to collapse. Sleep apnea causes one to stop breathing multiple times a night, which in turn causes brief periods of waking up to take a breath. People with sleep apnea do not remember these short awakenings and feel that they slept through the entire night. Sleep apnea may be treated by using a mask that delivers air through the nose which prevents airway collapse. Surgical treatment that enlarges the airway may also be affective.Filed under: Misc, Misc