We spend a large part of our life sleeping. Actually we sleep a third of our life time. This seems obvious, but if you ask to someone .. WHY.. do we sleep, there will be almost nobody able to give a concrete answer.

Sleep is one of those funny things about being a human being -- you just have to do it. Have you ever wondered why? And what about the crazy dreams, like the one where a bad person is chasing you and you can't run or yell. Does that make any sense?

We all know how sleep looks like -- when we see someone sleeping, we recognise the following characteristics:

1. If possible, the person will lie down to go to sleep.
2. he person's eyes are closed.
3. The person doesn't hear anything unless it is a loud noise.
4. The person breathes in a slow, rhythmic pattern.
5. The person's muscles are completely relaxed.
6. During sleep, the person rolls over or rearranges his or her body. This happens once or twice an hour. This may be the body's way of making sure that no part of the body or skin has its circulation cut off for too long a period of time.

In addition to these outward signs, the heart slows down and the brain does some pretty funky things (we'll get to this later).

At several points during the night, something unexpected happens -- rapid eye movement (REM) sleep occurs. Most people experience three to five intervals of REM sleep per night, and brainwaves during this period speed up to awake levels. If you ever watch a person or a dog experiencing REM sleep, you will see their eyes flickering back and forth rapidly. In many dogs and some people, arms, legs and facial muscles will twitch during REM sleep. Periods of sleep other than REM sleep are know as NREM (non-REM) sleep. REM sleep is when you dream. If you wake up a person during REM sleep, the person can vividly recall dreams. If you wake up a person during NREM sleep, generally the person will not be dreaming.

You must have both REM and NREM sleep to get a good night's sleep. A normal person will spend about 25 percent of the night in REM sleep, and the rest in NREM. A REM session -- a dream -- lasts five to 30 minutes.

HOW MANY HOURS MUST YOU SLEEP?

Most adult people seem to need seven to nine hours of sleep a night. This is an average, and it is also subjective. You, for example, probably know how much sleep you need in an average night to feel your best.

The amount of sleep you need decreases with age. A newborn baby might sleep 20 hours a day.

By age four, the average is 12 hours a day. By age 10, the average falls to 10 hours a day. Senior citizens can often get by with six or seven hours a day, and even 4 till 5 hours sleep is for some of us just enough….It's not how long you sleep …but the quality of sleeping that counts…

WHY SLEEP?

One way to understand why we sleep is to look at what happens when we don't get enough:

1. As you know if you have ever pulled an all-nighter, missing one night of sleep is not fatal. A person will generally be irritable during the next day and will either slow down (become tired easily) or will be totally wired because of adrenaline.
2. If a person misses two nights of sleep, it gets worse. Concentration is difficult, and attention span falls by the wayside.
3. After three days, a person will start to hallucinate and clear thinking is impossible. With continued wakefulness a person can lose grasp of reality.

A person who gets just a few hours of sleep per night can experience many of the same problems over time.
Two other things are known to happen during sleep. Growth hormone in children is secreted during sleep, and chemicals important to the immune system are secreted during sleep. You can become more prone to disease if you don't get enough sleep, and a child's growth can be stunted by sleep deprivation.
But the question remains -- why do we need to sleep?
No one really knows. There are all kinds of theories, including these: I. Sleep gives the body a chance to repair muscles and other tissues, replace ageing or dead cells, etc. II. Sleep gives the brain a chance to organise and archive memories. Dreams are thought by some to be part of this process. III. Sleep lowers our energy consumption, so we need three meals a day rather than four or five. Since we can't do anything in the dark anyway, we might as well "turn off" and save the energy.

What we all know is that, with a good night's sleep, everything looks and feels better in the morning. Both the brain and the body are refreshed and ready for a new day.

Good Night ….. and Sweet Dreams………