Sleep is "natural, temporary loss of awareness" necessary for our bodies to build up energy reserves and regenerate body cells and tissues. During sleep, the heart beats more slowly, breathing becomes slower, growth hormones peak, muscles relax and body temperature lowers. Newborn infants sleep almost incessantly, gradually decreasing their need for sleep. In early childhood, 12 to 13 hours of sleep are generally required and this quantity decreases to approximately 8 hours in adulthood. After the age of 50, sleep is frequently characterized by regular night moment wakenings, shorter dream lengths and less generally sleep.

Sleep disorder

Some causes of sleep disorders or insomnia include:

Pain experienced at night following injury, trauma or certain conditions e.g. arthritis.
Stress
Emotional trauma or mental anguish
Environment including noise and light levels
Geopathic stress
Jet lag
Aging
Nightmares and other dreams that interfere with adequate sleep
Over excitement
Too many electrical appliances in the bedroom

Sleep comfort

Getting a good night's rest refreshes the body, brain and feelings. It is as vital to our health as good food and exercise. The phrase "beauty rest" is more than a quaint idea, it is a basic task in the quest for external and internal loveliness. Many consider sleep to be of low priority among the many daily activities engaged in. It is estimated that the world's population is depriving itself of one less hour of sleep per night than is needed (Awake!, 2004). Despite this view of night-time rest, sleep is a necessary, sophisticated procedure regulated by the brain. Operating as a 24- hour clock, chemical substances, for instance melanin, are released in the body to begin sleepiness.

Stage of sleep

There are two main stages of sleep classified according to eye movement. The initially is REM or fast eye movement which is a shallow, dream-filled sleep. The second major stage of sleep is non-REM, or non fast eye movement, where blood pressure drops and heart rate slows as the person enters a deep sleep. There are four sub-stages within REM sleep. The first sub-stage lasts 30 seconds to 7 minutes, and during this time the muscles relax while the brain produces irregular wave activity. The second sub-stage lasts 20 percent of the night and brain waves become bigger as the body is asleep. The subsequently sub-stage is called delta sleep, where development hormones peak, and cell and tissue restore take place.

Sleep Deprivation

Sleep deprivation, flush short term, can be hazardous if driving a car, other operating machinery. Sleep deprivation is thought to be the reason of half of all interchange fatalities on U.S. Highways, and being aware 17 to 19 hours can cause the same limited response and ability as having a 0.05 percent blood alcohol limit. It is also implicated in many workplace accidents. Short term sleep deprivation causes little physical harm, since the body compensates for the lack of sleep by growing its adrenaline levels during the day. The body also attempts to obtain more sleep at a shortly time. A temporary shift in attitude may occur, such as feelings of pessimism or negativity (Bricklin, 1990). Chronic sleep deprivation, which is caused by prolonged shortages of sleep, can lead to paranoia or hallucinations. This is well termed 'sleep debt', and is characterized by jagged sleep patterns that do not tolerate the body to go in delta sleep. This can bring on a short attention span, memory and vocabulary loss as well as other symptoms.