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Friday, October 10, 2014


"If sleeping and dreaming do not perform vital biological functions, then they must represent nature's most stupid blunder and most colossal waste of time."-Anthony Stevens

Sleep is an activity of the brain, by the brain and for the brain. We spend nearly about one-third of our life asleep, yet we are still not sure why do we sleep. This is a question that has baffled scientists for centuries and the answer is, no one is perfectly sure. We have to sleep because it is essential to maintaining normal levels of cognitive skills such as speech, memory, innovative and flexible thinking. In other words, sleep plays a significant role in brain development. Our internal body clock governs our daily rhythm or circadian rhythm - telling us when to wake up and when to feel sleepy. [Circadian comes from the Latin circa, meaning about and dies, meaning day]. Sleepiness occurs as the circadian element causes the release of the hormone MELATONIN and a gradual decrease in core body temperature, So the longer you are awake and the more tired and sleepy you become, the greater the urge for you to fall asleep and the longer you are likely to sleep in order for your body to attain "normal function" again.. Sleep occurs in a recurring cycle of 90 to 110 minutes and is divided into two categories: NON-REM SLEEP(which is further split into four stages, These stages are defined in terms of brainwave patterns, which can be measured by an electroencephalograph (EEG).. ) and REM SLEEP (Rapid eye movement). Adults spend about 20% of their sleep time in REM and 80% in NREM sleep NREM SLEEP


It is the transitional period of very light sleep. Although the muscles and breathing rate begin to relax, the individual can still be awakened easily. We are half awake and half asleep.


Our eye movements' stop and our brain waves (fluctuations of electrical activity that can be measured by electrodes) become slower. The breathing pattern and heart rate start to slow down. This period accounts for the largest part of human sleep.


The brain begins to produce delta waves, a type of wave that is large (high amplitude) and slow (low frequency). Breathing and heart rate are at their lowest levels.


Main features are rhythmic breathing and limited muscle activity. If we are awakened during deep sleep we do not adjust immediately and often feel disoriented for several minutes after waking up. By waking them up each time they get to stage 4 sleeps, and then they complain of being physically tired Stage 3 & 4 are known as SLOW WAVE SLEEP. After stage 4 sleep the person enters into REM SLEEP. Then this cycle repeats till the end of sleep mostly without stage 1.


The first rapid eye movement (REM) period usually begins about 70 to 90 minutes after we fall asleep. REM sleep is also called "paradoxical" sleep because brain wave activity is similar to an awakened state.Our eyes move around (hence the name), our breathing rate and blood pressure rise. Typically, a person has four or five periods of REM sleep during the night. Visually intense dreaming occurs primarily during REM sleep,{But nightmare occurring during NREM sleep}. Since brain blocks signals to the muscles, our bodies will be effectively paralyzed, which is said to be nature's way of preventing us from acting out in our dreams. Many of our physiological functions such as brain wave activity, breathing, and heart rate are quite variable when we are awake or during REM sleep, but are extremely regular when we are in NON-REM sleep. After REM sleep, the whole cycle begins again. In each succeeding cycle, NON-REM stages shorten and the REM periods grow, giving us a 40-minute dream scape just before waking.REM sleep is believed to be connected with brain's way of registering new information. The relative amount of REM sleep varies considerably with age.


"The eye of man had not heard, the ear of man had not seen, man's hand is not able to taste, his tongue to conceive, nor his heart to report, what my dream was." -William Shakespeare

Dreaming has fascinated humankind since the dawn of history. As dreaming is so vivid, so complex and so emotional. It has inspired religious movements, artistic representations and scientific theories. At the turn of the twentieth century, Sigmund Freud came with book "INTERPRETATIONS OF DREAMS ".Dreams, in Freud's view, were all forms of wish-fulfillment - attempts by the unconscious mind to resolve a conflict of some sort, whether something recent or something from the remote past. Now science has grown in such a way that that it associates every form of mental activity with a similar form of brain activity. Therefore, if we detect a dream form, we can seek a corresponding brain form. During REM sleep the 'cortex of brain 'is highly active and activity in the brain triggers certain neurons at random (activation). The brain then tries to make sense of this by synthesizing the random impulses into what we experience as dreams, for example a cell triggering the area of the brain that controls balance may lead to a dream of falling. Dreams also plays a role in long term memory consolidation, But exact mechanism remains unknown. As the chemical systems that are responsible for recent memory are completely turned off when the brain is activated during sleep, it is difficult to have recall unless awakened. There is no evidence that the content of dreams has a significant influence on waking behavior.

Like all biological functions, sleep length varies widely. Animal and human studies suggest that the quantity and quality of sleep have a profound impact on learning and memory.The amount of sleep each person needs depends on many factors, including age. Infants generally require about 16 hours a day, while teenagers need about 9 hours on average. For most adults, 7 to 8 hours a night appears to be the best amount of sleep, although some people may need as few as 5 hours or as many as 10 hours of sleep each day. The exact amount sleep required by each individual is that much hours of sleep, which keeps him/her fresh & energetic next day.

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