Sleep seems quite a bit like the fuzzy subjects. A specialized body of science reports of intricate activities happening based on "invisible" information, in this case our brainwaves. Yet we appear to do nothing more than close our eyes and stop interacting with the outside world each night. Sleep is anything but inactive. Behind the scenes, the bodies of every human and most animals perform tasks necessary for good health and survival. This universal phenomenon aligns with the circadian nature of the planet earth.


A Look at Normal Sleep
Every human-in fact every mammal-sleeps. For that matter, all creatures, be they plants, fish, or exotic animals, alter their body function according to the rising and setting of the sun. But what is sleep? It doesn't look like much of anything. Our body stops moving about, eyes close, and the outside world has to stimulate us into wakefulness to get our attention during a period of slumber. As we shall see, the brain and body are quite busy during sleep.

What Is Sleep?

A period of biological rest or of one of vital physiological activity? A more accurate definition recognizes sleep as an exchange or alteration of certain body functions. So what goes, what stays and when? Human earthlings experience three types of tasks in regard to normal levels of consciousness:

Waking: internal tasks that require an awake, conscious body. Waking activities include sensing, interpreting, and responding to the universe. Our metabolism and other functions is regulated according to our level of activity. Engagement in conscious activity includes:

  • sensing the world around us
  • interpreting sensory experiences
  • thinking our thoughts
  • performing our actions
Ultimately...wakefulness provides us with all conscious experience, but it cannot occur without sleep.

tasks requiring a sleeping, unconscious body. Sleeping activities include metabolic processes that rejuvenate the body after a period of wakefulness and which cannot be performed while awake. For example, certain hormones are only released during sleep. Sleep is essential to survival.

those bodily functions that are performed during both wakefulness and sleep, such as circulation and breathing. Constant functions may alter their speed or intensity but never cease to continue, as long as we are alive.

Sleep is also related to a biological process called
Homeostasis. Homeostasis is the body's ability to stabilize internal functions (temperature, water and sodium levels, blood pressure, and sleep) by compensating for disruptive change. The hypothalamus, a part of the brain involved with regulating these functions, contains the internal pacemaker for sleep.


Index of  
Sleep Disorders