Sleep | DreamBoost.com

Sleep

By Darien Simon, M.S.

In many ancient cultures, including Rome, sleep was considered a divine gift:

"It was the time when first sleep begins for weary
mortals and by the gift of the gods creeps over them most welcomely."
Virgil (Roman poet,1st century B.C.), Aeneid II

Sleep has been recognized as necessary to health:

"Sleep's the only medicine that gives ease."
Sophocles (Greek dramatist, 5th century B.C.), Philoctetes, 766

"The beginning of health is sleep."
Irish proverb

And as a multipurpose essential part of life:

"Sleep that knits up the ravell'd sleave of care,
The death of each day's life, sore labour's bath,
Balm of hurt minds, great nature's second course,
Chief nourisher in life's feast."
Shakespeare, Macbeth Act II, Scene 2

But no matter how poetic the description, no one truly understands what sleep is, or why we do it for nearly a third of our lives. We know it is vitally important to life and health, since very unpleasant consequences follow its lack. Up until about 50 years ago, it was thought that sleep was necessary to rest the body and mind. However, recent research has shown there is considerable activity going on during sleep, so it's purpose must be something other than just rest.

Members of all the groups of the animal kingdom, even insects, sleep. Due to the different lifestyles of animals, different ways to sleep have evolved: standing up, perched on tree limbs, swimming through water, curled up on the ground or a bed. But as far as we know, only mammals and birds have developed two types of sleep: REM and non-REM.

In non-REM sleep, your body can move freely, though movements are infrequent. There are four stages of non-REM sleep: 1 and 2, comprising light sleep and 3 & 4, which are deep sleep. The stages are defined by their characteristic types of movements of body and eyes, and brain activity. For example, in light sleep, alpha waves are predominant, but in deep sleep, alpha waves give way to delta waves. One noticeable difference between alpha and delta states is the ease or difficulty of rousing from them. The alpha of light sleep is easy to leave behind. You wake up without grogginess or disorientation. But the delta of deep sleep leaves you feeling half asleep and half awake for a while. When you first go to sleep, you progress through the stages in order, then pass into REM sleep. From REM, you go back to stage 1, and repeat the cycle. In one night, you may cycle through the sequence several times, each cycle taking approximately 90 minutes. The first REM sleep cycle is usually short, about 10 minutes, but later ones may be two or three times as long. As the night progresses, each cycle contains less deep sleep and more REM sleep, until REM sleep makes up about 25% of your sleep time. Infants spend about 50% of their sleep time, often 2/3rds of the day, in REM sleep.

In REM sleep, the free movement of your body ceases, while your breathing becomes shallower and more rapid and irregular than in deep sleep. You also have jerky rapid eye movements (hence the name "REM" sleep), and you dream. Most, but not all, dreaming occurs during REM sleep, and REM dreams are more vivid than dreams in any other stage of sleep.

While no one has yet solved the mystery of why we sleep, researchers have discovered evidence that the old sayings were true: health does depend on sleep, but not in terms of rest or downtime. Rather, health and well-being depend on healthy sleep patterns to facilitate necessary repairs, consolidate memory, exercise little used neural connections, and conserve body energy.

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