"I will lie down and sleep in peace, for You alone, O Lord, make me dwell in safety" (Psalm 4:8).
My dearest friend,
When I was very, very young, my parents taught me this bedtime prayer:
Now I lay me down to sleep,
I pray the Lord my soul to keep.
If I should die before I wake,
I pray the Lord my soul to take.
As a tot, my life rested in the palm of God’s hand. Forty-five years later, nothing has changed! Like everyone else in this troubled world, I surrender myself to sleep each night. I am totally dependent upon Jesus, my Creator. Christ Jesus—He protects me when I dream—He protects us all. From the greatest, richest, and most powerful person on earth to the helpless infant, we are each sustained by the Lord’s gentle touch.
"I lie down and sleep; I wake again,
because the Lord sustains me" (Psalm 3:5).
All creatures sleep, some more than others. Did you know, for instance, that a cat spends twice as much time asleep than it does awake? Or that a horse sleeps only three to four hours each day? Sleep, whether brief or lengthy, places us at some risk, though. We are vulnerable to attack from others, yet God protects us (Psalm 4:8). Jesus designed every living thing to depend on Him in this way. Sleep is a natural expression of praise toward its Creator. When the eyes of a child or a hummingbird or a tiny frog close to rest, they bow in worship before God their Maker.
But what is sleep, and do all creatures rest in exactly the same way? Let’s consider my dog, Annika. She lies down in a familiar spot at night. Her muscles relax, her breathing slows, and her eyes stay closed while she is resting. During this time, Annika is much less aware of the activity around her than when she’s awake. This is the typical pattern of sleep for most animals, and people too.
Not all animals are alike though. Cows, horses, and snakes can sleep with their eyes open. And, of course, a fish naps eyes-wide-open because, well, it has no eyelids! Most quadrupeds (a quadruped is an animal with four feet) lie down to rest, but horses are able to sleep standing up, locking their legs in place. Like many animals, however, a giraffe must get off its feet at night.
Sometimes God’s creatures are forced to sleep “on the fly.” Migrating birds traveling over open ocean cannot land to rest. They may spend several days in flight and must literally sleep on the wing. During spring and autumn migrations, birds tend to sleep in 30-second intervals, gliding as they dream. Of course, a snooze any longer than this could be disastrous!
The same is true, in principle, with sea mammals. Research has shown that dolphins and seals have a very unique way of dozing without drowning. Christ Jesus fitted a dolphin with lungs, not gills, and it must breathe air to survive. Unlike a fish (a dolphin is a mammal, not a fish), it cannot stop swimming lest it sink and drown. It was once believed that killer whales and other marine mammals simply did not sleep. Careful study of these creatures has proven this idea wrong. The Lord Jesus, in a flare of brilliant engineering, designed the dolphin nervous system so that one half of its brain can sleep at a time.
The brain of all mammals is composed of two halves, called hemispheres. When a dolphin, killer whale, or seal gets tired, one half of its brain goes to sleep. The other hemisphere remains fully awake, allowing the animal to gently paddle close to the surface where it can breathe. After an hour or so, the portion of the dolphin’s brain that is asleep wakes up, and the other half dozes. Using this alternating method, dolphins can sleep seven hours a day. (I wish I could have mastered this technique in my college classes!)
Of the thousands of species of animals God created, the sleep habits of only 200 have been studied in detail by scientists. It is believed that all animals sleep, even insects! You might find the following chart interesting. It compares the amount of sleep for a few different creatures:
Obviously, we shouldn’t judge a bat as lazy just because it sleeps all but four hours every day. The amount of time each animal rests is God-ordained, and it shows His sovereignty in such matters.
If we examine the amounts people sleep, we note a wide range depending on age:
HUMAN — HOURS ASLEEP EACH DAY
fetus — practically all the time
newborn — 16 to 20
young child — 12
young adult — 8
elderly — 6 to 7
It’s clear that we sleep less and less as we get older, but this doesn’t mean we always get as much sleep as we need. (I’ll share more on this with you a little later.)
Using special equipment, it’s possible to determine how much a person dreams. An unborn child dreams virtually all the time while inside Mom, and a newborn infant spends about half its crib-time dreaming. Adults, on the other hand, dream approximately 30 percent of the night away. Yet, our dreams don’t come all at once.
When we first drift off in bed our sleep is rather light. It’s during this initial stage of sleep that we are easily stirred and woken up, say by a barking dog. After several minutes of light sleep we go into a period of deep sleep from which it is very hard to awaken. Next, we proceed again to light sleep, followed by dreams. A person cycles between light sleep→deep sleep→light sleep→dreams throughout the night. A complete sleep cycle of an adult occurs every 90 minutes. Thus, a person who sleeps eight consecutive hours will experience, on average, five or six separate dreams! (An average person’s dreams last about 25 to 30 minutes at a time, but ornithologists (scientists who study birds) have discovered that the dreams of a bird are only five seconds in duration.)
A child’s sleep cycle lasts around 50 minutes, so he or she dreams more frequently than an adult like myself. By contrast, an elephant dreams once every two hours; a cat, every 15 minutes. The grand prize goes to the mouse, however, who dreams every nine minutes. (What a mouse dreams about, I don’t know—maybe the cat?!)
The cadence of our dreams (every 90 minutes in adults; every 50 minutes in children) is only one way the Lord Jesus set our bodies to a precise time-schedule. We also follow a 24-hour cycle called the circadian (sir - KAY - dee - en) rhythm. Our bodies shut down for sleep, and wake up again, automatically every 24 hours. This circadian rhythm is present in animals and plants as well. It is not uncommon to see flowers opening in the morning at precisely the same time each day. (For instance, some flowers open at 4 A.M., some at 7 A.M., while other species unveil at 11 A.M. each and every morning.) With the daily setting of the sun, songs birds faithfully flock to the safety of their nocturnal homes, often a tree or bush. And springtime frogs and summer crickets usually begin their nighttime serenades at some predictable hour in the evening. All these activities are controlled by the circadian rhythm.
The 24-hour “clock” that determines the circadian rhythm in humans is located in the hypothalamus (high - po - THAL - ah - miss) at the base of the brain. Our body temperature, hunger, thirst, and the time we go to bed at night are all controlled by the hypothalamus. Now that I’ve explained this to you, I need to correct something I’ve just said. The hypothalamus clock is actually set to a 25-hour day, not 24 hours, as we might expect. People have voluntarily gone into deep, dark caves, where there is no natural light, and lived there several days. They took with them no clocks or watches or any other means of knowing what time it was outside the cave. What researchers found is very interesting. If the cave-dweller falls asleep at 10 P.M. the first night, he or she will fall asleep at 11 P.M. the next night, 12 midnight on the third night, and so on. In other words, the modern troglodyte is living by a 25-hour day.
If our hypothalamus is urging us to fall asleep one hour later, how come we go to bed and wake up at the same time each day? Our incredibly caring Creator provides us with a way to daily “reset” our internal clock. The thing that “tells” our hypothalamus that we live in a 24-hour, not 25-hour, world is the Zeitgeber (zite - gay - bur). Zeitgeber is a German word that means “time giver.” There are several Zeitgebers our Lord Jesus uses to keep us on schedule, but by far the most potent is the sun.
The sun rises and sets at approximately the same time each day, and this solar regularity keeps our hypothalamus tuned to a 24-hour schedule. You may be asking yourself why God placed a 25-hour clock within us—why not a 24-hour clock? Well, if our bodies were strictly controlled by a 24-hour internal clock it would be virtually impossible for us to travel to a foreign land. If I flew to Great Britain from Colorado, but I had no way to reset my circadian rhythm, I would be permanently seven hours out of sync with the English people. In other words, I would always be going to bed about the time they were waking up. The daily synchronization of our 25-hour clock to the sun permits a person to travel! The Lord allows us to reset our sleep schedule by simply using daylight. If Christ Jesus had not given us a way to adjust to foreign time zones, the Christian would never be able to fulfill the Great Commission (Matthew 28:19-20). Our Creator has thought of everything!
Our ability to perceive the passing of time is also affected by body temperature. This makes sense if we remember that the temperature of our bodies is controlled by the hypothalamus. Have you ever noticed that when you run a high fever, you’re more likely to become impatient waiting for something (for instance, you ask someone to run to the store to get some juice or over-the-counter flu medicine)? That’s because the clock inside your hypothalamus is ticking away more briskly than normal, making 30 minutes seem like an hour.
I hope you’re not too confused by all this, because the timing mechanisms within our bodies are really a little more complicated than I’ve outlined above. The Lord Jesus has also created within us a 12-hour clock. This means that every 12 hours we get sleepy. The time of the day when most people are the sleepiest is between one and four in the morning. Twelve hours later, around one to four in the afternoon, most people will again feel tired. This afternoon slump in energy has nothing to do with lunch—even if you skip lunch you will likely experience fatigue at this time of day.
The afternoon dip is not as strong as the early morning lull, so we don’t necessarily fall asleep then. However, in many countries—particularly those in Central and South America—people customarily take an afternoon nap called a “siesta.” The popularity of the siesta has nothing to do with the outside temperature. People in Siberia experience the same urge to sleep on a wintry afternoon as someone living in Mexico! (It may be of interest to you that God also designed the lion and the tiger to rest twice a day. So the siesta is certainly not a sign of weakness!) Most Western nations frown on people taking an afternoon nap, but one wonders if we shouldn’t do this more often?!
My friend, this brings me to my final point. It is possible in the rush of our modern society to become chronically fatigued due to lack of sleep. Many people spend their days being sleep-deprived because they go to bed late every night. (I have been guilty of this.) Sleep debt may not seem like a serious problem, but it is the cause of many accidents in the workplace. And physicians have discovered that sleep-deprived people are more prone to infections. Conversely, when we’re sick, we sleep more—proper rest is vital to recovery from illness. Research has shown that our immune system works better when we sleep.
In addition, persons who forego sleep tend to experience moodiness and difficulty with concentration. They become irritable and depressed. Severe sleep debt can lead to slurred speech, heart murmurs, and weight loss. An otherwise normal person can even experience paranoia and hallucinations!
Our Heavenly Father is an awesome Protector. He gives us a time to rest and a time to wake. We all must forego sleep at critical times in our lives, but to perpetually ignore our need for God-given rest is foolhardy. There is a proper balance between too much and too little sleep. The Lord Jesus created us for His own glory—let’s honor Him with our work AND our sleep!
WHEN CREATION SLEEPS... GOD IS HONORED!
"There is a time for everything, and a season for every activity under heaven..." (Ecclesiastes 3:1).