Eight hours a day, 56 hours a week, 224 hours a month, 2688 hours a year. That adds up to one third of our life. This is the average time a person spends sleeping. It seems like an awful lot a time wasted on inactivity. However, sleep is not about inactivity. The electroencephalogram (EEG) is a summation of activity of postsynaptic cerebral neurons. The changes the brain goes through during sleep is measured by the EEG. These measurement show that the brain is not inactive during sleep. The brain, more than any other organ, undergoes a repair process during sleep.
Sleep consists of two fundamental states, REM and non-REM sleep, and each cause a distinct pattern of activity in the brain. During Non-REM sleep most of the muscles relax, body systems take a rest, and the brain waves associated with wakefulness and alertness disappear and are replaced by increasingly slow, deep waves of inactivity. In the REM stage of sleep, though muscles are totally relaxed, your eyes move back and forth quickly, your heartbeat increases, and blood flow to the brain is increased. This stage recurs about every ninety minutes throughout the night and each time it recurs we spend a little longer in this stage.
In normal sleeping patterns a person usually passes through five stages of sleep. It begins with stage one and goes to a deep sleep known as stage four. These stages are all during the time known as Non-REM sleep or non-rapid eye movement sleep. The first stage is a very light sleep with relaxed muscles. The second stage is characterized by brain waves getting larger. The third and fourth stages are where the sleeper is in a deep sleep in which their brain waves are huge and slow which make this stage the hardest to wake from. After an hour or so, you shift into a highly active stage characterized by rapid eye movement or REM sleep. In this stage the brain waves are almost as if you were awake. Dreaming occurs in all stages of sleep.
Stage one is the transitional period between wakefulness and sleep. In this stage, you become less aware of your surrounding, more relaxed with breathing more regular and there is more slow, rolling eye movement. This is the lightest stage of sleep and last for about 10 minutes before a person moves on to the next stage.
Stage two is the first stage of true sleep and accounts for about 50% of total sleep. Still considered a transitional stage, you become less aware of your surroundings. This phase is still considered light sleep, as you are easily aroused from this sleep state.
Stage three and four are considered stages of deep sleep. In stage three extremely slow brain waves called delta waves begin to appear, interspersed with smaller faster waves. By stage four, the brain produces delta waves almost exclusively. During this stage you become very relaxed. Your have a slow regular heartbeat and respiratory rate. It is very difficult to be awakened during this stage. If you are awakened, you become confused and slow to react. It is usually easy to fall back asleep.
At one time REM sleep was thought to be a dormant state, in fact, the brain is quite active during this stage of sleep. After reaching stage four the pattern of progressively slower, larger brain waves and deeper sleep begins to reverse and sleep becomes light until the REM sleep state is reached. REM is the most active part of sleep. The brain, when viewed using EEG, have a pattern that is most similar to those of a person who is awake. REM sleep occurs cyclically every 90 minutes during the night in association with high brain activity, rapid spontaneous eye movements and suppressed voluntary motor activity.
The phrase sleeping your life away seems to be less relevant. Studies and research prove the importance of sleep and the role it plays in our ability to live full, active and productive lives.
