In mammals, there are two types of sleep — rapid eye movement (REM) and non-REM (NREM). They are defined in terms of electrophysiological signs that are detected with a combination of electroencephalography (EEG), electroculography (EOG) and electromyography (EMG), the measurement of which in humans is collectively termed polysomnography.
Researchers find that sleep involves five distinct patterns - four stages of successively deeper sleep known as non-rapid eye movement sleep (or NREM sleep), and a fifth stage known as rapid eye movement, or REM, sleep. NREM sleep is divided into four stages, corresponding to increasing depth of sleep, as indicated by progressive dominance of the EEG by high-voltage, low-frequency ('synchronized') wave activity. Such low-frequency waves dominate the deepest stages of NREM (stages III and IV, also termed slow-wave sleep).
During NREM sleep, the brain waves tend to become slow and more regular, and the people lies fairly still and breathes slowly and regularly. Any snoring that takes place will be during NREM sleep. The four levels of NREM sleep are known as stages 1, 2, 3 and 4. It is in stage 4, the deepest level of sleep, that the electrical activity is slowest.
REM sleep is a much lighter sleep. Its distinguishing feature is that the eyes intermittently dart about under closed eyelids; hence the term "rapid eye movement". At the onset of REM sleep, any snoring ceases, breathing becomes irregular, and both the flow of cerebral blood and brain temperature increase. There are also more body movements. The electrical activity of the brain is similar to that in stage 1 sleep. During this stage your brain waves are almost the same as when you were awake. But it makes sense that your mind needs to process, resolve, or let go of thoughts, impressions, and feelings (charges).
During our sleep we go into REM stage several times. Research indicates the importance of REM sleep. The more REM sleep you get, the more likely you will get up feeling refreshed, positive, and energetic. When you sleep 7 to 8 hours you will probably experience 4 to 5 REM sleep episodes. However, the first REM period doesn’t last very long.
The person will progress through these five stages in cycles, each cycle lasting about 90 minutes. After falling asleep, a healthy adult will slip into stage 1 sleep, which gives way to 2, to 3 to 4; then the sequence goes into reverse. After the second period of stage 1 sleep, the cycle is completed by between 5 and 15 minutes of REM sleep. The sequence is repeated four or five times, with the portion of REM sleep increasing in each cycle while the NREM portion (especially stages 3 and 4) decreases. A person sleeping for around 8 hours will spend about two hours in REM sleep, and the remainder in NREM sleep.
This pattern of NREM and REM sleep, especially the 90 minute cycle, is remarkably similar from one human to another. For example, people with a condition called narcolepsy suffer an uncontrollable urge to fall asleep. No matter where they are or what they are doing, sleepiness will suddenly overtake them.
Young mammals experience a much greater proportion of REM sleep than normal adults. A newborn baby who sleeps around 16 hours a day will spend at least half of that in REM sleep. With premature babies, the percentage of REM sleep is even higher - around 75 per cent. A newborn kitten, puppy, rat or hamster experiences only REM sleep.
Some researchers believe that REM sleep is essential for the human brain to mature before and after birth, and that this explains why babies need so much sleep. The small amount of time that the newborn guinea pig spends in REM sleep supports this hypothesis: compared with a helpless kitten or puppy, a guinea pig is "mature" at birth.
Alpha waves
The rhythm of the brain waves are measured in cycles per second (CPS). When you are awake and alert, the CPS of your brain waves are 14 and up. We call these waves Beta waves.
When you relax deeply, your brain waves have about 7 to 14 CPS. These waves are called Alpha waves. This stage occurs naturally when you are about to fall asleep and when you wake up but are not quite there yet. When you learn how to fully relax and meditate you will enter the Alpha state as well. To go into Alpha is very rejuvenating for mind and body. The mind loses its rigidity. Knowledge and experiences are more easily integrated. Thinking becomes more creative. And insights spontaneously occur. Go into Alpha when you need to problem solve or when you want to make important decisions, relax, energize, center and focus. For example, alpha waves are generated by the relaxed brain, so that you have vivid memories, aha moments, and you feel at peace with the world.
For a restful sleep it is important that your serotonin level (neurotransmitter) is as high as possible. Serotonin increases a feeling of well-being, which helps to slow down and to initiate a calm peaceful sleep. Directly related to the production of serotonin is the production of melatonin, a hormone which is known for its sleep-inducing effect. Serotonin and melatonin use the same building blocks: tryptophan. Basically everything that we have discussed, and will be discussing relating to feeling good, is applicable to helping you improve your sleep cycle as well.
Brain-wave activity ranges from fully awake to deep dreamless sleep. This activity is categorized into five primary groups: Delta, Theta, Alpha, and Beta.
Delta 0.1-3 Hz deep sleep, lucid dreaming, increased immune functions
Theta 3-8 Hz deep relaxation, meditation, increased memory, focus, creativity, lucid dreaming, trance state, hypnosis
Alpha 8-12 Hz light relaxation, "super learning", positive thinking, light trance, hypnosis
Beta >18 Hz fully awake, normal state of alertness, stress and anxiety
At your peak performances your mind is energized by the highest brain waves – called beta waves. Start to daydream during a lecture, or boring committee meeting, and your brain waves shift down a gear to alpha brain waves. You’re still awake but your waves would register lower on an EEG which is a reading that measures brain waves by hooking electrodes to several points on your head.
Move down one further level – to theta waves and your body relaxes, heart rate and respiration lower slightly, and your mind tends to move back and forth between creative energy and deep relaxation. Eventually, the lowest brain waves, called delta waves, kick in, and for awhile the brain moves back and forth between delta and theta movement.
In the first stage of sleep, EEGs show the brain waves slowing down progressively through a thirty minute period. Your brain at that point shifts into REM or rapid eye movement sleep.
Nathaniel Kleitman, discovered in the 1950s, that is REM sleep a person’s eyes flutter rapidly in all directions. In REM stages of sleep people dream, and when woken in that stage you may feel like a truck hit you – but you will likely remember your dreams. Interestingly brain waves at the deepest sleep speed up again – even though the brain remains dormant to conscious thought.
Serotonin chemicals are released which is characterized by high performance and researchers tell us that when some people begin to move from alpha waves into theta movement, sleep soon follows. People who practice meditation can train their minds to enter meditative states, much as those practiced by monks or devote Zen followers.
In contrast, the stress hormone cortisol is release in dangerous doses in people who sustain stress in the lives. This can be caused by poor diet, lack of priorities, too little sleep, habits such as meta messages which generate poor relationships, and lack of reflection that helps you grow and progress in daily doses.
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