“And God saw the light, that it was good: and God divided the light from the darkness. And God called the light Day, and the darkness He called Night. And the evening and the morning were the first day.” Genesis 1:4–5. In the beginning, when God created the world, on the first day He created Day and Night, light and darkness. He intended that man would have a daylight period in which to work, followed by a rest period which would occur when the sun went down.
Let us look at two concepts: Man was created with the need for a period of rest or sleep every 24 hours; and God designed that this would be accomplished in the darkness He called Night.
The rest period that God gave to man served a very important purpose. We all feel fatigued after a hard day’s work and our bodies need a period of rest to recover. But, is sleep solely for physical recovery, or does sleep provide other health benefits? Sleep is necessary for survival. If sleep deprivation lasts for too long, death will occur. Lack of proper sleep also affects the immune system in detrimental ways, leaving us more susceptible to infections and disease. It is also necessary for our nervous systems to work properly. Too little sleep leaves us drowsy and unable to concentrate the next day. It also leads to impaired memory and physical performance, as well as reduced ability to carry out complex calculations. If sleep deprivation continues, hallucinations and mood swings may develop. Sleep also gives neurons (brain cells) used while we are awake a chance to shut down and repair themselves. Without sleep, neurons begin to malfunction. Sleep also may give the brain a chance to exercise important brain cell connections that might otherwise deteriorate from lack of activity.
The average sleeper takes about 7 minutes to fall asleep. Children fall asleep faster than the elderly. As we sleep, we pass through five different stages, from a very light sleep in Stage One where it is easy to be wakened, to the deepest part of sleep in Stage Four, then to the stage that allows us to dream, called REM (rapid-eye movement) sleep. During REM sleep, dreams can be very intense, as our brains are more active during this stage. We move through the five stages of sleep in about 90–110 minutes. During the deep stages of non-REM sleep is when the body repairs and regrows tissues, builds bone and muscle, and strengthens the immune system. Babies can spend up to 50% of their sleep in the REM stage, compared to only about 20% for adults. REM sleep stimulates the brain regions used in learning. This may be important for normal brain development during infancy, which would explain why infants spend much more time in REM sleep than adults. Babies and children also have longer periods of deep sleep, which is why it seems that they can sleep through anything. As we get older, the amount of deep sleep decreases.
During the deepest part of sleep, growth hormones are released in children and young adults. Many of the body’s cells also show increased production and reduced breakdown of proteins during deep sleep. Since proteins are the building blocks needed for cell growth and for repair of damage from factors like stress and ultraviolet rays, deep sleep may truly be “beauty sleep.” Activity in parts of the brain that control emotions, decision-making processes, and social interactions is drastically reduced during deep sleep; this rest helps maintain peak emotional and social functioning while awake. Learning and memory is also improved during deep sleep. Students who deprive themselves of sleep, cramming for a test or memorizing school work are affecting their ability to retain what they have learned.
How much sleep do we need? There are people who claim they can function on just 4–6 hours of sleep each night; however, adults who receive fewer than seven hours of sleep, even for just one night, have difficulty concentrating, impaired judgment, slowed reaction times, poor hand-eye coordination, and have more mood problems than people who sleep at least seven hours a night. Studies among adults also show that getting less than seven hours of sleep a night is associated with increased rates of heart disease, and death from all causes overall. Driver fatigue is responsible for an estimated 100,000 motor vehicle accidents and 1,500 deaths each year in the United States. Since drowsiness is the brain’s last step before falling asleep, driving while drowsy can—and often does—lead to disaster. If your sleep is frequently interrupted or cut short, you are not getting quality sleep. The quality of your sleep is just as important as the quantity. We need to cycle through the various stages to get proper, restorative sleep. Disrupting the cycle impairs the quality of sleep, even if we are woken briefly by noise, going to the washroom, or from pain.
The length of sleep that is needed differs with age. Infants and toddlers can sleep up to 13 hours in a 24-hour period, which includes naps; school age children need 9–11 hours of sleep at night; adults need 7–8 hours of sleep a night. However, some adults can function on less, and others may need nine hours of sleep a night. The amount of sleep that each person needs varies from individual to individual. The amount of sleep needed tends to be determined by heredity.
Have you ever lay in bed, wide awake, unable to get that beautiful restorative sleep that you know you need in order to stay awake and function at a level that you need for the following day? What do you find usually keeps you from getting a good night’s sleep? Is it the thoughts of all tasks that you need to complete? Is it worrying about the health of a family member? How about the spiritual condition of someone you love? Perhaps it is something simple as outside noise, especially for those who live in crowded cities. Or, are you trying to sleep during the day for various reasons? There are many reasons for poor sleep which have effects on your health, both on a short-term and a long-term basis.
As people get older, they sleep more lightly and get less deep sleep. Aging is also linked to shorter time spans of sleep, although the amount of sleep needed is the same as when people were younger. Often older adults nap during the day to make up for lost quality and quantity of sleep during the night. As we get older, our sleep also tends to be less restorative. Some of this is part of the natural aging process; however, some sleep problems can arise from poor health. Deterioration in sleep follows general health to a closer degree than it does true chronological age. For those who suffer from heart conditions such as high blood pressure, heart attacks, stroke and heart failure, sleep is especially compromised. Sleep problems unrelated to other health conditions also tend to get progressively worse with age, including sleep disorders such as insomnia, sleep apnea, circadian rhythm disturbances, and restless legs syndrome. More about this next month.
In our modern, fast-paced world, sleep appears elusive. Most people need to wake themselves up with some sort of alarm to get up in time for work, to take their children to school or to run all the errands that are needed. Not many of us are able to sleep every night and wake up when our body tells us that we are ready to awaken, restored and refreshed. We often do not get the sleep that we need. Most of the world today is chronically sleep deprived. The amount of sleep that adults receive has been decreasing over the past 50 years to an average of seven hours or less a night. Technology, which has sped up the performing of mundane tasks of everyday life, has not lengthened the amount of sleep that people get. Most of us can function if we have one night of poor sleep, but for a lot of people, this is not the case.
Sleep is regulated by two body systems. When we have been awake for a long period of time, “sleep/wake homeostasis” tells us that the need for sleep is accumulating and that it is time to sleep. It also helps us maintain enough sleep throughout the night to make up for the hours of being awake. In this way, sleep/wake homeostasis creates a drive that balances sleep and wakefulness.
The second system is the circadian rhythm. The circadian rhythm dictates that there are ideal times within each 24-hour time period for our body to sleep, eat, and do activities. The hormonal and chemical changes that your body goes through in its circadian rhythm support certain functions that you should be doing during certain phases of the 24-hour period. Your circadian rhythm controls your sleep/wake cycles—it wants you to wake up in the morning when the sun comes out and go to sleep at night when it is dark out. As it gets darker out, your brain produces higher doses of melatonin, a hormone produced by our body, which signals that it is time to go to sleep and makes you drowsy. Before the era of electric lights, people would go to bed when it got dark, and woke up when the sun rose again in the sky, with the sleep/wake cycle staying in tune with the body’s circadian rhythm. Now, with artificial lighting, we can have light 24 hours a day and our working hours are not dependent on the light from the sun. No longer do people only sleep when the sun goes down. Many people work shift work, or travel across time zones, or have illnesses which alter sleep patterns. What implications do all these have on our health? We will learn more about this next month.
“Sleep, nature’s sweet restorer, invigorates the weary body and prepares it for the next day’s duties.” –Counsels on Health, p. 147. “Give yourself proper time to sleep. They who sleep give nature time to build up and repair the weary waste of the organism.” –Medical Ministry, p. 80