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Why Do We Need to Sleep?
Why Do We Need to Sleep?

Why do we sleep? This is a question that has baffled scientists for centuries and the answer is, no one can be sure. Some believe that sleep gives the body a chance to recuperate from the day's activities but in reality, the amount of energy saved by sleeping for even eight hours is minuscule - about 50 k Cal, the same amount of energy in a piece of toast. We need 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.

What can happen if we didn't sleep?

A good way to understand the role of sleep is to look at what would happen if we didn't sleep. Lack of sleep has serious effects on our body's ability to function. If you've ever pulled an all-nighter, you'll be familiar with the following after-effects: grumpiness, grogginess, irritability and forgetfulness. After just one night without sleep, concentration becomes more difficult and attention span shortens considerably.

With continued lack of sufficient sleep, the part of the brain that controls language, memory, planning and sense of time is severely affected, practically shutting down. In fact, 17 hours of sustained wakefulness can lead to a decrease in performance equivalent to a blood alcohol level of 0.05% (two glasses of wine).

Research also shows that sleep-deprived individuals often have difficulty in responding to rapidly changing situations and making rational judgments. In real life situations, the consequences are grave and lack of sleep is said to have been be a contributory factor to a number of international disasters such as Exxon Valdez, Chernobyl, Three Mile Island and the Challenger shuttle explosion.

Sleep deprivation not only has a major impact on cognitive functioning but also on emotional and physical health. Sleep apnea which result in excessive daytime sleepiness have been linked to stress and high blood pressure. Research has also suggested that sleep loss may increase the risk of obesity because chemicals and hormones that play a key role in controlling appetite and weight gain are released during sleep.

What happens in our body when we sleep?

What happens to our body and how does it happen every time we get a bit of shut eye? Sleep happens in a recurring cycle of 90 to 110 minutes and is divided into two categories: non-REM (which is further split into four stages) and REM sleep.

What is Non-REM sleep

Stage one: Light Sleep
During the first stage of sleep, we're half awake and half asleep. Our muscle activity slows down and slight twitching may occur. This is a period of light sleep, meaning we can be awakened easily at this stage.

Stage two: True Sleep
Within ten minutes of light sleep, we enter stage two, which lasts around 20 minutes. The breathing pattern and heart rate start to slow down. This period accounts for the largest part of human sleep.

Stages three and four: Deep Sleep
During stage three, 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. Stage four is characterized by rhythmic breathing and limited muscle activity. If we are awakened during deep sleep we do not adjust immediately and often feel groggy and disoriented for several minutes after waking up. Some children experience bed wetting, night terror, or sleepwalking during this stage. We encourage you to visit a Sleep Specialist if you or your child experiences any of these symptom.

What is REM sleep

The first rapid eye movement (REM) period usually begins about 70 to 90 minutes after we fall asleep. We have around three to five REM episodes a night. Although we are not conscious, the brain is very active - often more so than when we are awake. This is the period when most dreams occur. Our eyes dart around (hence the name), our breathing rate and blood pressure rise. However, our bodies are effectively paralyses, said to be nature's way of preventing us from acting out our dreams. After REM sleep, the whole cycle begins again.
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Related Links
• National Sleep Foundation - Website
• American Academy of Sleep Medicine - Website
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