Sleep

On February 19, 1985, China Airlines Flight 006 left Taipei, Taiwan, for an 11-hour trip to Los Angeles, California. About nine and a-half hours into the flight the number 4 engine lost power, and the flight crew began to try to restore power. While they were concentrating on that task, the captain failed to monitor his instruments properly, and the plane rolled over and began a nosedive toward the ocean. The plane fell from 41,000 to 9,500 feet before the captain managed to regain control. The plane sustained severe structural damage, and two passengers were seriously injured during the incident, which exposed the plane to a force five times that of normal gravity.

Lack of sleep or irregularity of sleeping hours may have been an important factor in this incident. The pilot lost control of his plane during hours when, for the past six days, he had been asleep.

At 3:58 a.m. on April 13, 1984, two freight trains sped toward one another on the same track. In the cab of Burlington Extra 6714 the engineer and other crew members had fallen asleep. The two trains collided head-on near Wiggins, Colorado, destroying seven locomotives and killing five crew members.

Investigators cited irregular shifts and crew members' decisions not to sleep during their off time as contributing factors.

A questionnaire filled out by 1,000 train engineers revealed that 11 percent would admit to dozing off on most night trips, while another 59 percent admitted to at least one dozing-off period some time on the job. No daytime engineers admitted to dozing off on most trips, but 23 percent had done so at least once on a day trip.

A leading sleep researcher stated-recently that more accidents occur from sleepiness than alcohol consumption. Single-vehicle, air transport, and military accidents have a greater probability of occurring at night. Flight simulation studies have shown that a pilot's ability to fly a simulator may be impaired at night as much as it would be by a blood alcohol level of 0.05 percent.

Sleep is important no one will deny that. But in the midst of a hectic schedule, when there is more to do than there is time to do it, it is tempting to begin to think of sleep time as lost time. So many try to get by with less hours in bed by staying up late or geting up early, then trying to make up for the lost sleep time with hurried catnaps.

Effects of sleep loss

But the effects of cutting back too far on sleep time soon become evident. The effects are most readily evident in small children. We've all watched crankiness and sibling fighting increase when children miss their naptimes on a busy day.

Adults are better at masking their hostility. Nonetheless, the psychological effects of sleep deprivation include in creased irritability, anger and antisocial behavior, and the breakdown of normal ego defense mechanisms. Without enough sleep, people generally become more serious, listless, and grim. Spontaneity disappears, and extended sleep loss can lead to disorientation, paranoia, depression, and inability to maintain focus on a task. Perceptiveness also decreases, as do cognitive reasoning abilities and psychomotor capabilities.

Sleep loss also affects physical capabilities, such as the ability to make fine hand movements and focus the eyes. It leads to increased sensitivity to pain, reduced muscle tone and strength, in creased reaction time, and difficulty maintaining good posture. If sleep deprivation continues long enough, death results. Studies conducted on rats have shown that when body temperature be gins to drop dramatically because of sleep loss, death occurs within days, even if the animals are allowed to resume sleeping.

Recent sleep research indicates that it is not only how many hours you sleep but also the regularity of your sleeping schedule and the duration of the sleeping period that allow you to get the benefit you need from sleep.

What happens when you sleep

Sleep is by no means a passive wasting of time. Sleep time is divided into two main divisions: rapid-eye-movement (REM) sleep and non-rapid-eye-movement (NREM) sleep. NREM sleep is further subdivided into stages 1, 2, 3, and 4, with increasing numbers representing deeper sleep. Stages 3 and 4 are called slow-wave sleep (SWS), or deep sleep. Each of these divisions of sleep is an active physiological process.

REM and NREM sleep each has its own physiological functions. A typical night's sleep is made up of four to six approximately 90-minute cycles that be gin in stage 1, then proceed to deeper and deeper sleep, then to less-deep sleep, then to REM, then back through the series like this: stage 1, 2, 3, 4, 3, 2, REM, 2, 3, 4, 3, 2. As the night progresses, the amount of SWS decreases and REM in creases. As morning approaches, stage 4, and sometimes stage 3, are eliminated from the cycle.

Apparently REM sleep is involved with mental processing of new information, the transfer of material from short-term to long-term memory, and in some way with the control of what is called animal motivate drive behavior. Translated into common terms, this means that animals deprived of REM sleep show increased sexual drive, sexual deviance, pleasure and food seeking, and decreased grooming. REM sleep is also important in many bodily functions because it affects secretion of several body chemicals, including cortical steroids.

The amount of time we spend in REM decreases as we grow older. A premature infant may spend as much as 80 percent of its sleep time in REM, while full-term infants are in REM only about half of the time they are asleep. By young adulthood REM makes up only 10 to 20 percent of sleep time, and in later years this decreases even further.

Slow-wave sleep (stages 3 and 4) is important for recovery from fatigue, and increases after increased physical labor. It is characterized by high-amplitude, slow-frequency EEG activity of less than four cycles per second; by resting muscle tone and slow, regular cardiac and respiratory rates; by increased blood flow to the muscles; and by constriction of brain arteries. SWS also decreases with age. While it averages 10 to 20 percent in young adults, it may be entirely absent in the elderly.

How much is enough?

We have all known people who seem to be able to function well on only four or five hours of sleep per night. But such people are the exception rather than the rule. Most of us need between seven and nine hours of sleep each night, and a recent study revealed that even those who thought they were getting enough sleep benefited from getting an extra half hour or hour.

A healthy newborn infant sleeps around 16 hours, and this decreases to 11 hours by age 3 to 5, 10 hours by age 10, and 7.75 hours by age 19. This decline seems to continue slowly with age until in their 60s and 70s many people sleep only five to six hours per night. Elderly people tend to awaken more frequently and for longer periods than younger adults.

Studies have revealed that the average North American and European sleeps seven to eight hours per night. A recent study of 12 European countries and the United States showed that 25.3 percent of men and 29.1 percent of women slept less than seven hours per night, whereas 14.6 percent of men and 13.7 percent of women slept longer than nine hours. Most people sleep longer on weekends, which indicates that they may be depriving themselves of needed sleep during the workweek.

Perhaps the best way to determine how much sleep is enough for you is to go to bed early enough to awaken naturally without an alarm clock. Allowing your own body to determine how much sleep you need can help prevent the chronic sleep deprivation that is prevalent in industrialized nations.

How to improve your sleep

Facts about sleep may be interesting, but what most of us are interested in is how to get a good night's sleep. If you suffer from insomnia, you may need to go to one of the sleep study departments that have recently been instituted at several universities. Some problems can be diagnosed only through thorough testing. In an article published recently in the Washington Post Magazine, the author told of his 20-year struggle with nightly wakefulness. He tried all kinds of folk remedies and wonder cures, but continued to wake up several times every night, finding himself unable to get back to sleep for hours on end.

Only after being hooked up to an apparatus that tracked his brain waves and muscle tension all through the night did he learn that what woke him up several times during the night was twitching legs. Doctors at the research center prescribed medication that alleviated the twitching, and he has been able to sleep better ever since.

For most of us, though, getting better sleep may be simply a matter of eliminating a habit that disturbs our sleep, or starting a practice that can enhance sleep.

Among the things that can inhibit good sleep are alcohol and other psychoactive drugs, lack of exercise, and habit patterns.

Alcohol's relationship to sleep is particularly significant. While alcohol may help a person to fall asleep, it decreases the quality of sleep. It disrupts the cycles of sleep stages and inhibits REM sleep. Even moderate levels of prenatal alcohol exposure can lead to disturbance of sleep cycles in newborns. And infants born to alcoholics experience inhibition of REM sleep. The real tragedy is that this may contribute to their becoming alcoholics themselves. REM sleep deprivation of rat pups has been found to increase their adult alcohol consumption.

Such drugs as antihistamines, antihypertensives, and nearly all psychotropic drugs, including marijuana, affect sleep, increasing daytime sleepiness and disrupting various sleep stages. Marijuana in infants exposed prenatally interferes with sleep cycling, lessens SWS, in creases body movements, and lessens characteristic markers of REM sleep, regardless of the trimester of exposure.

Smoking is another factor associated with sleep difficulty. Smokers take significantly longer to fall asleep, and they awaken for longer periods after falling asleep than do nonsmokers. In addition to the increased latency of sleep onset and more frequent arousals, smokers also appear to get less sleep (between .17 and . 85 hours less per night) than nonsmokers, and tend to have as much as three times as many nightmares and dreams.

Many people report feeling tired and sleepy for several days just after quitting smoking. Fortunately, this sleepiness not only affects them during the day; it also extends into their regular sleeping hours. Abrupt cigarette withdrawal brings about a total time awake decrease of 45 percent on the first three nights of abstinence. This gain comes partly from falling asleep faster and partly from less episodes of wakefulness during the night.

Habits that improve sleep

Two of the most important things you can do to improve your sleep are to get into the habit of getting enough exercise and to abide by a regular schedule for sleep whenever possible.

Studies have shown that exercise decreases the time it takes to get to SWS, and that physically fit individuals obtain more SWS than unfit individuals. As in most things, moderation is the key here. If you haven't been getting enough exercise, start out with light exercise and work up to more strenuous exercise as your level of fitness increases. Strenuous exercise can actually lead to sleep disturbances for the unfit, and exhausting exercise can produce the same result even in those who are physically fit. Any exercise done just before going to bed should be light to moderate, because heavy exercise tends to excite the central nervous system and cause sleep disturbances.

Exercise in the late evening may also tend to raise your metabolic rate and keep you warmer. Since sleep depresses body temperature, a delay in the lowering of your body temperature may keep you awake longer. Of course, the same problem may result from trying to sleep in a room that is too warm.

A regular schedule for going to bed and getting up can also help you get more and better sleep. In a study of a group of adolescents suffering from moderate sleep disturbances, all that was necessary to overcome their problems was rigorous stabilization of bedtime and wake-up time on weekdays and weekends.

And regularity of sleep has more benefits than just better sleep. Maintaining a stable sleep-wakefulness cycle is necessary for optimal levels of subjective mood and behavioral performance as well. Among college students, regularity of re tiring and awakening hours is the exception rather than the rule. But those who adhere to a regular sleep schedule show greater achievement potential, intellectual efficiency, self-control, and sociability. Studies of sailors have yielded similar results. Good sleepers outperformed poor sleepers in fulfillment of duties and tended to be promoted more rapidly.

Three additional suggestions for promoting better sleep involve what you do just before and after you "hit the hay." If you like to read just before going to bed, read light material, preferably something unrelated to your work. Don't watch television right up to bedtime, because the excitement and tension generated can make it hard to get to sleep. And if after you're in bed you find it hard to get to sleep, don't just lie there getting more frustrated by the minute. Get up and read something that is relaxing. Staying in bed and fighting to get to sleep can be come a habit that will make it hard to fall asleep every night.

Whatever you do, it is important to do your best to resolve any problems you may have with getting enough sleep. A recent National Institutes of Mental Health study revealed that unresolved sleep problems are strongly related to development of serious depression.

"When thou liest down, thou shalt not be afraid: yea, thou shalt lie down, and thy sleep shall be sweet" (Prov. 3:24) is one of the most precious promises in the Bible. A good night's sleep can help give you the strength you need to cope with even the most challenging of days.