A Wake-Up Call
A Wake-Up Call
Americans and Sleep
By: Stanley Coren
Source: Stanley Coren. Sleep Thieves: An Eye-Opening Exploration into the Science and Mysteries of Sleep. New York: The Free Press, 1996.
About the Author: Stanley Coren is a psychologist. A prolific writer in his field, Coren has published scholarly texts, monographs, and several hundred journal articles. His areas of particular interest are sensation, perception, and neuropsychology. He has received numerous awards and honors by his peers as well as by professional organizations. Coren also wrote a best-selling series of books for dog owners.
Both sleep researchers and the media describe the United States as a nation of people who, on the whole, fail to get enough sleep on a regular basis. Sleep is lost in an effort to balance the demands of work, family, assorted commitments, and the stresses of day-to-day living. Often as adults, and sometimes as children, there are too many time demands to fit into a normal day, and sleep time is sacrificed in an effort to meet responsibilities.
Numerous scientific and practical reports state that adults function best after receiving an average of eight hours of sleep nightly. Children require more sleep, and adolescents more still. However, most American adults sleep only about six hours nightly. People vary widely in their sleep needs, with some needing up to ten hours to feel at their best, others spontaneously awakening, and feeling sleep-satiated after only four or five hours. Sleep scientists have suggested that adequate sleep amounts (of seven to eight hours) per night offer some physiological protection against heart disease.
The ideal amount of sleep for an individual has been defined as the quantity that allows the person to awaken feeling refreshed, having an ample supply of energy to meet the demands of the day, and remaining generally healthy (not getting sick with excessive frequency). Another yardstick for sleep time is that amount that allows one to awaken spontaneously, without need of an alarm clock. Some researchers have written that a good way to determine optimal hours of sleep is to pay attention to patterns while on vacation, or in a situation in which there is no need to arise at a specific time. The number of hours slept is probably about what the body needs to feel optimally rested. However, it may take one a few days to accurately note the point at which this occurs.
There are a variety of factors that can interfere with getting enough sleep, or with experiencing high quality sleep. Individuals who sleep with pets, babies, or small children, or who sleep in beds too small or crowded for comfort, tend to lack quality sleep. People who work at or through the night, have rotating shift schedules, or have an infant or person who is very ill in the home tend to get sleep that is lower in quality and quantity than is ideal. Those who stay out late and have to get up early, or persons with very demanding lives, with stressful jobs, or large or highly time-intensive families, often experience sleep loss over prolonged periods. When that occurs, it is termed sleep deprivation. Sleep-deprived people tend on average to be more irritable, more prone to feelings of depression, and more emotionally labile; have less sustainable energy; have more erratic school, task, or work performance; have less efficient immune systems (and therefore get sick more often); and may even age (physiologically) at an accelerated rate. Several studies, in the United States and in Europe, have offered evidence suggesting that prolonged sleep deprivation may increase the likelihood of heart disease, type II diabetes, obesity, and hypertension.
Although sleep has been a subject of scientific research for decades, and of anecdotal study for as long as there have been curious humans, the specific and discrete reasons for its occurrence have not yet been determined. All living and mobile (that is, not rooted to a particular location) organisms have an innate need for sleep, and cannot survive without it for any prolonged period of time. Published research reports on the physiology of sleep have suggested that it aids in the maintenance of the immune system, allows the body time to repair and replace cells, facilitates metabolism, and allows the tired body to restore its depleted energy reserves. Some data has supported the possibility that sleep somehow facilitates the construction or strengthening of long-term memories.
There is a body of scientific evidence likening the biochemical and physiological effects of sleep deprivation to those of alcohol intoxication: both negatively affect gross and fine motor skills, hamper coordination, dull reflexes and response time, and impair judgment and critical thinking skills. Police and traffic monitoring agency statistics indicate that roughly 250,000 motor vehicle accidents per year result from drivers who fall asleep at the wheel. Lack of sleep slows reflexes, impairs coordination, and impacts judgment. It can, and does, lead to accidents—sometimes with tragic results. The National Commission on Sleep Disorders has estimated that sleep deprivation costs America $150 billion annually in increased stress and decreased work performance.
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David Dinges is a sleep expert working at the University of Pennsylvania. In his opinion, studies that looked at the timing of sleeping-driver-related-motor vehicle accidents across the course of the day suggest that there are large peaks (clusters of accidents) in the middle of the night and smaller peaks in the middle of the afternoon. He believes that the biological functions responsible for regulating brain activity also contribute to so-called "fall asleep" roadway collisions. In other words, humans have time periods during which their bodies rather critically need sleep, and people have a limited ability to fight off this physiological imperative.
The British Sleep Foundation has also targeted tired drivers, and likens driving while tired to driving while intoxicated. A study in Australia compared the relative effects on performance of alcohol and sleep deprivation, and found that severely sleep-deprived subjects performed as poorly as those with significant blood alcohol levels.
Among the most chronically sleep deprived individuals reported are night shift workers. British sleep researchers report that people who work at night and who try to sleep during the day are getting a poorer quality of rest, less deep sleep, and therefore fewer REM (rapid eye movement) cycles than those who work day shifts and sleep at night. Such chronic lack of sleep slows thinking and reaction time, making it more difficult for them to learn new skills or work efficiently.
A study conducted at the University of Chicago Medical Center concluded that cutting back significantly on required nightly sleep can produce large changes in glucose tolerance and endocrine functioning, comparable to what might be seen in the early stages of diabetes or of advanced age. This was a particularly important study, as it was much more like the real-world experience of people who are chronically sleep-deprived than studies in which subjects are entirely prevented from sleeping for prolonged periods. In the course of everyday life, people are more prone to smaller but chronic sleep losses, than to routine bouts of complete lack of sleep. At the height of the sleep debt study, volunteers took 40 percent longer than normal to regulate their blood sugar levels following a high carbohydrate meal, and their ability both to secrete, and to respond to, insulin each decreased by roughly 30 percent—a pattern similar to early clinical markers for diabetes. Sleep debt also decreased production of thyroid stimulating hormone and increased afternoon and evening cortisol levels. Those results are typical in senescence, and are believed to be associated with age-related health problems, such as memory impairment and insulin resistance.
Bush, Andrew J., et.al. Epidemiology of Sleep: Age, Gender, and Ethnicity. Mahwah, New Jersey: Lawrence Erlebaum Associates, 2004.
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