Healthy Sleep Habits, Happy Child Read online

  Strategies

  HEALTHY SLEEP

  Are your child's sleep patterns healthy? There are five elements of healthy sleep for children:

  Sleep duration: night and day

  Naps

  Sleep consolidation

  Sleep schedule, timing of sleep

  Sleep regularity

  When these five items are in proper balance, children get the rest they need. Let's first take a look at each one separately. Later, we will see how each element is not really independent from the others but simply part of a package called “healthy sleep.”

  As we consider the biological development of these five factors, please remember that parenting practices such as feeding do not influence how the brain develops. There are five turning points in the sleep maturation process: six weeks (night sleep lengthens), twelve to sixteen weeks (daytime sleep regularizes), nine months (disappearance of night waking for 14 feeding and a third nap), twelve to twenty-one months (disappearance of the morning nap), and three to four years (afternoon nap becomes less common).

  As your baby's brain matures, the patterns and rhythm of sleep change. If you always adapt your parenting practices to these changes, your child will sleep well. Those parents who do not see these changes or make these adjustments have babies who become overtired. The biological development causing all these changes is under the control of two regulatory mechanisms. Understanding these controlling mechanisms will help you organize your thoughts and plan your actions to ensure healthy sleep for your child.

  The first regulatory system controls the body's need for sleep and has been called the “homeostatic control mechanism.” In a nutshell, this means that the longer you go without sleep, the longer you will subsequently sleep. If you lose sleep, the body tries to restore it. The body tries to make sure you are getting enough sleep. This automatic process reflects an internal biological mechanism that we do not control. It is similar to the body wanting to control its temperature; when we get hot, we automatically sweat. If we do not drink enough fluid, then we cannot sweat, and we suffer the ill effects of dehydration. However, if we drink too much caffeine and deprive the body of sleep, we also cause harm. Unfortunately, our baby's biological need for sleep is always changing, so we have to be on our toes in order not to miss shifts in sleeping requirements.

  The secondary regulatory system has been called the “circadian timing system.” It is also called the “internal timing system” and can be thought of as a dedicated regulatory program that switches specific genes on and off in response to the light-dark cycle. This regulatory apparatus built to turn on and off is a molecular clock that is genetically specified and it is set to the proper time by sunlight. This mechanism automatically tries to ensure that the body is sleeping at the right time, and that when you are asleep, the timing and amounts of different stages and types of sleep are correct. Signals come from a specific area within the brain to make us feel sleepy or wakeful. The pattern of these signals changes over weeks, months, and years as the baby grows into an adult. The pace of these changes is especially quick during the first several months, so it is easy for a parent to get a little off tempo. Just when you think you have figured out when your baby needs to nap or be put to bed at night, the times change!

  IMPORTANT POINT

  The Internal Timing System is under genetic control so there is individual variation. It takes time for the Internal Timing System to express itself.

  Sleep Duration: Night and Day

  If you don't sleep long enough, you feel tired. This sounds very simple and obvious, but how much sleep is enough? And how can you tell if your child is getting enough sleep?

  Under three or four months of age, infants’ sleep patterns seem mostly to reflect the development of the child's brain. During these first few weeks, in fact, sleep durations equal sleep needs, since infant behavior and sleep durations are mostly influenced by biological factors. But after about three or four months, and perhaps even at about six weeks (or six weeks after the due date, for babies born early), parenting practices can influence sleep duration and, consequently, behavior. As I will discuss later in more detail, I believe parents can promote more charming, calm, alert behaviors by becoming more sensitive to their growing child's need to sleep and by helping to maintain healthy sleep habits. The goal is to recognize and respect your child's need to sleep and not do things that interfere with the natural sleep process.

  Newborns and Young Infants

  During their first few days, newborns sleep about sixteen to seventeen hours total each day, although their longest single sleep period is only four to five hours. It makes no difference whether your baby is breast-fed or bottle-fed, or whether it's a boy or a girl.

  PRACTICAL POINT

  Nursing mothers often worry unnecessarily that long sleep periods deprive their baby of adequate breast milk. Weight checks with the doctor will reassure you that all is well.

  Between one week and four months, the total daily sleep duration drifts down from sixteen and a half to fifteen hours, while the longest single sleep period—usually the night—increases from four to nine hours. We know from several studies that this development reflects neurological maturation and is not related to the start of feeding solid foods.

  Some newborns and infants under the age of four months sleep much more and others much less. During the first few months, you can usually assume that your baby is getting sufficient sleep. But if your baby cries too much or has extreme fussiness/colic, you might assist Mother Nature by trying the helpful hints for “crybabies” described in Chapter 4.

  PRACTICAL POINT

  When they are one or two weeks old, many infants begin to have several hour periods of increasingly alert, wakeful, gassy, and fussy behavior. This continues until about six weeks of age, after which they start to calm down. This increasingly irritable and wakeful state is often misinterpreted as resulting from maternal anxiety or insufficient or “bad” breast milk. Nonsense! The culprit is a temporarily uninhibited nervous system that causes excessive arousal. Relax; this developmental phase will pass as the baby's brain matures. It's not your fault.

  Young infants are very portable. You can take them anywhere you want, and when they need to sleep, they will. I remember when, as a medical student at Stanford University, I was playing tennis with my wife one day and my first child was sleeping in an infant seat near the fence. A huge dump truck came crashing down the narrow street, making an awful racket. We ran over to our son, only to be surprised that he remained sweetly asleep. After six weeks of age, he became more socially aware of people around him; after about four months of age, he, like all children, became interested in barking dogs, wind in the trees, clouds, and many other curious things, all of which could and did disturb his sleep.

  For some infants, the time when the baby first makes a socially responsive smile (usually at six weeks of age, or six weeks after the due date, for babies born early) is when social curiosity or social learning begins. However, under about three or four months of age, most infants, like my son, are not much disturbed by their environment when it comes to sleeping. When their body says it's time to sleep, they sleep. When their body tells them to wake up, they wake up—even when it is not convenient for their parents! This is true whether they are fed on demand or according to a regular schedule. It is also true even when they are continuously fed intravenously because of birth defects of the stomach or intestines. Hunger, in fact, seems to have little to do with how babies sleep. A much more likely candidate for influencing a baby's sleeping patterns is the hormone melatonin, which is produced by the baby's brain beginning at about three to four months of age. This hormone surges at night and has the capability to both induce drowsiness and relax the smooth muscles encircling the gut. So around three or four months of age, so-called day/ night confusion and apparent abdominal cramps (colic) begin to disappear.

  Furthermore, infants raised in an environment where the lights are constantly on evolve norma
l sleep patterns, just like babies brought up in homes where the lights are turned on and off routinely. Another bit of evidence to suggest that environment has little effect on sleep patterns in children under three or four months of age comes from infants born prematurely. A child born four weeks before his due date, for example, reaches the same level of sleep development as a full-term baby four weeks later than the child born on time. Biological sleep/wake development does not speed up in those preemies who are exposed to more social stimulation.

  What we can conclude, therefore, is that, for infants under three or four months of age, you should try to flow with the child's need for sleep. Don't expect predictable sleep schedules, and don't try to enforce them rigidly. Still, some babies do develop regular sleep/wake rhythms quite early, say at about six to eight weeks. These babies tend to be very mild, cry very little, and sleep for long periods of time. Consider yourself blessed if you are one of these lucky parents.

  Older Infants and Children

  As children age, the amount of time they sleep tends to decrease. Figures 1 through 3 describe how much daytime sleep, night sleep, and total sleep occur at different ages for older children. The bottom curve in each graph means that 10 percent of children sleep less than the amount shown, while the top curve means that 90 percent of children sleep less than the amount shown for each age. These curves were generated by my own research using data collected from 2,019 children, mostly white, middle-class residents of northern Illinois and northern Indiana in 1980. These graphs can help you tell whether your child's sleep is above the ninetieth percentile or below the tenth percentile. (Other studies have used only the fiftieth percentile, or average values, and do not tell you whether your child's sleep duration is slightly below average or extremely below average.) Interestingly, the results of studies of similar social classes in 1911 in California and in 1927 in Minnesota, also involving thousands of children, were the same as those in my study. In addition, studies in England in 1910 and Japan in 1925 showed identical sleep curves.

  So it seems that despite cultural and ethnic differences, social changes, and such modern inventions as television, DVDs, and computers that shape our contemporary lifestyles, the age-specific durations of sleep are firmly and universally rooted in our children's developing biology.

  An exception to this generalization is that adolescents in the United States are now getting less sleep. During the second half of the twentieth century, a trend toward earlier start times for high school developed. This forced children to get up earlier during the school week and reduced the total number of hours available for sleeping. At the same time, it became more popular for teenagers to hold part-time jobs after school, so they were going to bed later. Also, the amount of homework has increased.

  After about four months, I think parents can influence sleep durations, and as you will see, sleep durations for these older infants and toddlers are especially important.

  I studied sixty healthy children in my pediatric practice at five months of age and then again at thirty-six months. At five months of age, the infants who were cooing, smiling, adaptable, and regular, and curiously approached unfamiliar things or people, slept longer than infants with opposite characteristics. These easy and calm infants slept about three and a half hours during the day and twelve hours at night, or a total of fifteen and a half hours. Infants who were fussy, crying, irritable, hard to handle, irregular, and more withdrawn slept almost three hours less overall, almost a 20 percent difference (three hours during the day and nine and a half hours at night, or twelve and a half hours total).

  In addition, for all the five-month-olds studied, persistence or attention span was the trait most strongly associated with daytime sleep or nap duration. In other words, children who slept longer during the day had longer attention spans.

  As I will discuss in a later chapter, infants who sleep more during the day are better able to learn from their environment; this is because they have a better-developed ability to maintain focused or sustained attention. Like a dry sponge in water, they soak up information about their surroundings. They learn simply from looking at the clouds and trees, touching, feeling, smelling, hearing, and watching their mothers’ and fathers’ faces. Infants who sleep less in the daytime appear more fitful and socially demanding, and they are less able to entertain or amuse themselves. Toys and objects are less interesting to these more tired children.

  By three years of age, the easier to manage children in my study who were mild, positive in mood, adaptable, and approachable toward unfamiliar people slept twelve and a half hours total. The difficult to manage children—those who were intense, more negative, less adaptable, and withdrawing—slept about one and a half hours less, almost the equivalent of a daytime nap.

  An important conclusion is that three-year-olds who nap are more adaptable than those who do not. But napping did not affect the length of sleep at night. Comparing nappers and non-nappers, night sleep duration was ten and a half hours in both groups. Those who napped, however, slept about two hours longer during the day, so their total sleep was twelve and a half hours. Therefore, it simply is not true that children who miss naps will “make up” for it by sleeping more at night. In fact, the sleep they miss is gone forever.

  PRACTICAL POINT

  Missing a nap here and there will probably cause no harm. But if this becomes a habit, you can expect your child to lag further and further behind in his sleep and to become increasingly difficult to handle in this over-fatigued state.

  All in all, at age three, the children who slept more were more fun to be around, more sociable, and less demanding. The children who slept less not only tended to be more socially demanding, bratty, and fussy, but they also behaved somewhat like hyperactive children. Later, I will explain how these fatigued, fussy brats are also more likely to become fat kids.

  One recent study examined the effects of a single night of sleep restriction in a group of children between ten and fourteen years old. The researchers noted that there were impairments in verbal creativity, abstract thinking/concept formation, and in complex problem solving. These higher cognitive abilities appear to be essential for academic performance and success. In contrast, there were no deficits on rote performance or less-complex memory and learning tasks. The ability to maintain routine performance despite being sleepy is familiar to every adult who sometimes gets very tired but nevertheless is able to perform the routine aspects of his or her job fairly well. My interpretation of this study is that chronic sleepiness in infants and young children impairs cognitive development, but this will not become apparent until the child is much older and challenged by more complex tasks. Of course, cognitive development starts in babies, not at ten to fourteen years of age, but the deficits from sleep deprivation remain hidden in young children. When younger, the challenges are at a much lower level, and these chronically sleep-deprived children may still do well with spelling, writing, reading, and simple arithmetic. Later, when older, the more demanding academic challenges unmask the cognitive deficits.

  Looking at our sleep curves again, we see that throughout early and middle childhood, the duration of sleep declines until adolescence, when the curve shown in Figure 1 levels off and then slightly increases. This increase has been noted in other studies and suggests that teenagers need more sleep than preteens. Yet academic demands, social events, and school sports combine during adolescence to pressure teenagers to stay up later and later. Also, there are biological shifts in adolescents that seem to encourage more wakefulness in the evening. This is the time when chronic and cumulative sleep losses begin to take their toll, and can make a normally rough period in life unbearably rocky.

  Naps

  Having grown up in a highly achievement-oriented society, most American adults are likely to view naps as a waste of time. We tend to think that the adults who nap are lazy, under-motivated, ill, or elderly. In turn, we do not attach much positive benefit to daytime sleep in our infants and young children. Le
t me explain why naps are indeed very important for learning, or cognitive development, in children.

  Naps are not little bits of night sleep randomly intruding upon children's awake hours. Actually, night sleep, daytime sleep, and daytime wakefulness have rhythms that are partially independent of one another. During the first three to four months of life, these rhythms develop at different rates, so they may not be in synchrony. Only later do these sleep/wake rhythms become linked with fluctuations in body temperature and activity levels.

  For example, most of us have experienced drowsiness in the afternoon. This sensation is partially related—but only partially—to how long you have been up and how long you slept the night before. Our mental state fluctuates during the day between alert and drowsy, just as fluctuations occur during the night between light and deep sleep stages. As adults, an afternoon nap is most refreshing when we take it at the time when we are biologically most drowsy. Here is how to figure out your best nap time. Take the midpoint between the time when you most easily fall asleep at night (example: 10:00 P.M.) and most comfortably awaken naturally in the morning (example: 8:00 A.M.). Then, twelve hours from the midpoint is your best naptime (example: 3:00 P.M.). If you lived in the siesta belt, you might rest or take a nap, but in the United States, it's a coffee break.

  There is an important reason, though, why some adults do not nap: sleep inertia.

  Sleep Inertia

  Sleep inertia is a feeling of disorientation, confusion, pain, discomfort, impaired mood, and the inability to concentrate or think well that occurs upon awakening, especially from naps. In children, sleep inertia appears to be more severe and more prolonged for those who are more overtired. It appears that sleep is intruding into wakefulness and this overlap state is painfully uncomfortable. One mother described it as a “fugue” state, another as a “demonic” state. The children are out of control, panicky, crying, or screaming hysterically. Parents would often call me after three-day holiday weekends, during which their children became severely overtired, and tell me that they were sure their child had a painful ear infection because their child awoke crying. They often added that they were sure their child was not overtired because the child had just completed an extra-long nap! The ears were perfect. The children had simply missed some naps or had been allowed to stay up too late during the holiday.