Sleep is a naturally occurring condition of body and mind, characterized by decreased consciousness, inhibited physical activity, decreased sensory performance, decreased motor activity during deep sleep and decreased interactions with external environments during waking hours. The modern sleep disorder called sleep apnea exists when the airway is blocked by the tongue or some other obstruction during breathing while asleep. Sleep is crucial to the functioning of all organs in the human body, as it is during periods of wakefulness. Although sleep duration and quality have increased dramatically over recent years, researchers are not certain about the reasons for the increase in sleep duration and quality.
There are many different kinds of sleep, but the two most common sleep types are Rapid Eye Movement (REMS) and Non-Rapid Eye Movement (NREM), each with their own characteristics. REM sleep is the kind of sleep most desirable for those seeking to rest and recover from an exhausting day, but it is also associated with the kind of deep sleep that enhances creativity, emotional well-being and memory consolidation. NREM sleep is the kind of sleep most relevant to the development of the next day. Some experts believe that sleep onset REM sleep is more important than non REM sleep, but most agree that NREM sleep contributes to the health, safety and strength of the next day.
REM and NREM sleep have distinct sleep cycles. They normally occur during light sleep cycles and appear to last only several hours. Stage I and Stage II REMs are the most common in human beings, with Stage III being the rarest. REM sleep can be initiated by a minor stimulation, such as moving your hand or arms, and can be maintained through muscle relaxation and hypnosis. NREM sleep is usually induced through environmental, emotional or physical stress and can involve any number of symptoms such as: vivid dreams, nightmares, irritability, inability to concentrate and feelings of impending doom. The symptoms of NREM sleep are often mistaken for the symptoms of Stage IV sleep apnea, which is a life-threatening sleep disorder caused by obstructions of the breathing passages.
Sleep deprivation has been linked to a number of serious illnesses including heart disease, hypertension, diabetes, depression, Alzheimer’s and Parkinson’s disease. Lack of sleep has also been found to trigger the body’s natural response to hunger by causing increases in appetite. This means that when a person has insufficient sleep, the body releases hormones that prompt people to eat more food. Although the body does not usually overeat, the tendency to do so can be deadly. In the past, many of these same diseases were attributed to consumption of too much food; today, experts understand that lack of sleep can contribute to these conditions, but they do not believe that the lack of sleep causes the actual disease itself.
Other studies have shown that lack of sleep may also lead to less efficient brain functioning. According to a recent study, individuals who slept less than seven hours had significantly less efficient brain activity compared to those who slept seven to nine hours. Individuals who slept seven hours had better cognitive function and had better memory function than those who did not sleep enough. Although this study was performed on adults, it is possible that these results may also apply to children.
Another study links lack of sleep to an impairment in the formation of new memories. As the amount of time that the individual sleeps increases during the night, the amount of memories that are formed during the day become less. According to researchers, the human brain normally solves problems during the active stages of sleep, while forgetting some of the information during the inactive stages of sleep. As more time is spent in Stage I and Stage II, or Stage I and Stage III, of sleep, less information is stored, thus making it harder to solve problems when the person becomes awake. These results show that if the brain does not go to the REM (Rapid Eye Movement) stage of sleep during the inactive periods of the day, then problems related to memory will occur.