Schedules and Sleep Rhythm Disturbances
Schedules and Rhythms
Children commonly experience sleep disturbances caused by problems in the timing of their sleeping and waking patterns and in their daily routines. Their schedules may be too irregular; they may be regular, but inappropriate in certain ways; or a child may just not be sleeping when her parents want her to sleep. If your child’s daily patterns are inconsistent, then her sleep at night may be broken. If she naps or eats at unusual times, then she may wake too early in the morning or fall asleep too late at night. If she has become accustomed to sleeping at the “wrong” hours, then she may be unable to fall asleep as early or sleep as late as you wish.
Many sleep problems can be treated simply by adjusting the underlying sleep schedule. In other cases, an improper sleep schedule is only part of the problem, but still a very important one. If your child isn’t tired when you want her to go to sleep, you might rock her or give her a bottle to try to help her settle down, and in the process you may inadvertently teach her to associate these activities with falling asleep. Or, if you have difficulty setting firm limits at bedtime, your child may always stay up too late, and the time at which she gets sleepy may shift. When a child has a sleep problem that includes a disturbance in her sleep rhythm, it will probably not be enough simply to correct her sleep associations or set firmer limits at bedtime: you will have to correct her schedule as well.
To make corrections—in fact, to understand and treat any child’s sleep problem properly—you must first understand the rhythm of her sleep-wake pattern. When parents have trouble treating their child’s sleep problems, it is often because they haven’t considered her schedule. Whenever a family consults me about a child’s sleep problem, I always ask when their child goes to bed, when she actually falls asleep, when she wakes in the morning, and when she sleeps during the day. I also need to know when she is awake at night and for how long; whether she wakes on her own or has to be wakened in the morning and from naps; whether her schedule changes on weekends and vacations; and whether her schedule varies when cared for by different adults under different bedtime conditions, or in different sleep locations. Without at least this basic schedule information, it is impossible to make any informed recommendations.
Why is this information so critical? The answer has to do with the body’s circadian rhythms. The term “circadian,” literally meaning “approximately one day,” refers to changes in an organism’s biological systems that cycle approximately every twenty-four hours. Nearly all living things exhibit these rhythms. A branch of science called circadian biology studies them in plants and animals, and discoveries in this field have been truly astounding. Clever and sophisticated experiments have given us a much improved understanding of how circadian rhythms are set and how they control sleep and waking. With these scientific advances, our understanding of sleep and sleep problems in children has improved considerably, and we can use this knowledge to develop rational treatment programs.
The circadian control of our body rhythms begins before birth, and the same basic pattern of control persists across all ages. The main concepts discussed here apply equally well to adults and children. The regular alternation between sleeping and waking is an obvious example of this circadian pattern, but in fact all of your body’s physiological systems follow a daily cycle as well. There are predictable daily variations in hormone levels, body temperature, intestinal activity, urine output, and even immune system function. Steroid levels drop at night and rise toward morning; body temperature does the same. The level of melatonin, a hormone secreted by the pineal gland, rises at night in the dark and drops during the day in the light.
None of this happens by coincidence. These cycles are all controlled by the “biological clock,” also called the circadian, or central, pacemaker. This pacemaker consists of a group of cells located in the hypothalamus, a primitive area of the brain that, in addition to its circadian effects, also directly governs minute-to-minute changes in hormone levels, appetite, blood pressure, and other basic functions. In humans, the circadian pacemaker tends to run a little slow: if we allowed it to run freely, it would take about ten minutes longer than a standard twenty-four-hour day to complete one cycle. Yet we normally operate (or should operate) on an exact twenty-four-hour day. We manage that by resetting the pacemaker every morning, just as you might reset your watch every day if it tended to run slow.
In humans, the only proven way to adjust the clock (other than with certain medications) is through exposure to light. Light travels into your eyes and stimulates your retina; some of that information is relayed directly to the biological clock in the hypothalamus, in effect telling the clock the correct time. If the clock’s current internal setting is incorrect, it starts to adjust in the appropriate direction. That is why your body normally runs according to your local time, and why you can adjust your schedule when you travel to a different time zone. (The reason it takes several days to adapt to a new time zone is that, except in specialized laboratory settings, our biological clocks cannot make large adjustments all at once.) Light affects the clock differently depending upon what “time” it is inside your body when the exposure occurs: light at noontime has very little effect, but light after sunset or toward morning makes your body think the day ends later or starts earlier, and so the clock adjusts in the corresponding manner.
Activities, meals, and napping can affect your clock’s setting, but only indirectly, by changing the hours you are exposed to light. If you stay up later than usual after an evening nap, or if you get up extra early one morning for an appointment, you will be exposed to light at times when you would normally be asleep. And if you are used to eating in the middle of the night, you will definitely be exposed to light at the wrong time.
Certain regular and predictable aspects of our daily schedules develop through habit or necessity, regardless of the circadian pacemaker’s setting. For example, although we generally feel hungriest near our typical meal times, if we force ourselves to eat at different times we will eventually learn to get hungry at those times instead, even if the rest of our daily schedule—including when we sleep—is unchanged. To a degree, even nap times can be changed independently of nighttime sleep hours.
If meals, napping, and daytime activities do not follow any regular schedule, our physiological rhythms become disorganized and uncoordinated, and feelings of hunger and sleepiness begin to occur at unpredictable and inappropriate times of the day. If we don’t sleep regular hours at night, this disorientation worsens: now these rhythms no longer function in concert at all, as they should. Our bodies do not seem to know whether it is time for a snack or a big meal, for a brief evening nap or an early bedtime. Some of our circadian rhythms may be set for sleep while others are at levels associated with waking.
“Jet lag” is the same phenomenon in another guise. When you first travel to a different time zone, your body’s clock remains set to the time zone you left. You try to conform to the new schedule, staying awake and active during the daylight hours and sleeping when it is night there. But your body, unable to reset its internal clock instantly, wants to wake and sleep at times based on the clock at home. As your rhythms adjust to the new time zone, they may do so at different rates; thus, for a while, not only are they at the wrong setting but they are also out of sync. You feel drowsy and unwell during the day and you sleep poorly at night.
If you follow the new schedule consistently, your circadian clock and all the physiological systems under its control will eventually adjust. But if you don’t keep to a regular schedule—perhaps while traveling or even routinely at home—your rhythms may never work in harmony. If you are a shift worker, the symptoms are probably familiar: you have to try to sleep when you feel wakeful and get up when you want to sleep. If you change shifts too frequently, your sleep rhythms cannot stabilize: at home you may continually suffer from sleep problems, and at work you may never feel fully awake.
The term sleep phase refers to the period of time that starts when you (or your child) become sleepy enough to fall asleep for the night and ends when you wake spontaneously in the morning after getting all the sleep you need. If, because you don’t get enough sleep during the week, you are tired enough to fall asleep unusually early some nights or to sleep extra late in the morning, it may be difficult to determine your sleep requirement and your sleep phase exactly; they will be easier to determine when you are on vacation. However, it is usually easy to make a very good estimate of how much daily sleep children need and what times of the day and night they are capable of getting it (see Chapters 1 and 2).
If you want to get a real sense of how your sleep phase affects you and the way you feel, stay up all night reading a book. The evening will probably go by without trouble. However, after a while you will begin to feel sleepy. This point of “sleep readiness” often comes on quite suddenly. Now your eyes no longer stay open of their own accord—in fact, it becomes a struggle to keep them open and focused—and it becomes difficult to pay attention to your reading. You may feel cold and want to get under a blanket. If you gave in and allowed your eyes to close, you would probably be asleep within a minute or two. These signs mean that you have passed from your wake phase into your sleep phase, or (using different terms that mean the same thing) from your wake zone into your sleep zone. Now it’s easier to fall asleep than to stay awake.
If you fight off the sleepiness, you may find that after half an hour or so you briefly feel more awake; but soon the sleepiness returns again, even more powerfully. This alternation between periods of (relatively) heightened and lessened alertness, known as the “basic rest-activity cycle,” continues all night and through the day as well, but the overall tendency is to grow sleepier during the night and to become more alert toward morning. If you stay awake until perhaps four o’clock in the morning, you will probably feel terrible. All your body rhythms are set for sleep. Your temperature and steroid levels are low, you may be a little nauseated, and the thought of staying awake for the entire upcoming day is awful. But if you manage to remain awake a few hours more, until the point in the morning at which you would ordinarily wake up spontaneously—the end of your sleep phase and the start of your wake phase—you will notice a surprising improvement: all your body rhythms are switching back to “wake.” (Hunger is a good sign that you have reached this point.) After a shower and some breakfast, you probably won’t feel all that bad, even though you have had no sleep at all.
What you’re experiencing is the effect of your circadian system. Your body moves into “wake” mode whether you have slept or not. If you are like most people, you can tolerate a single sleepless night without great impairment. In fact, you probably won’t go to sleep much earlier than usual the next night (that is, your sleep phase will not shift earlier to compensate for the lost sleep), and that night you probably won’t sleep much more than usual.
The key point to remember is that it is hard to sleep in your wake phase and hard to stay awake in your sleep phase. This idea will be important in Chapter 10, when we start to discuss sleep schedule problems.
The Circadian System and the Forbidden Zone for Sleep: Why You Can Stay Awake Until Bedtime—and Sleep Until Morning
If you were to graph your level of alertness while you stayed up all night, the result would be a rough U-shaped curve: you get progressively sleepier, then start to feel more awake toward morning. On a normal night when you’re sleeping, the pattern is a little different: there is a “bump” of lightened sleep and (potentially) increased alertness in the middle of the night (see Figure 9). That’s why it’s often easier to get up to use the bathroom at 3:00 A.M. than it is an hour after falling asleep or an hour before your usual wake-up time.
The pattern of alertness during the daytime is similar. Rather than following a simple inverted U curve, or even just declining from morning to night, alertness during the day follows roughly a mirror image of the nighttime pattern, with a “dip” in the middle of the day corresponding to the nighttime “bump”: you do become fully alert soon after waking, and you do get progressively sleepier as the day goes on, but you go through a stretch of especially low alertness in the midafternoon (again see Figure 9). Children on a one-nap schedule take their nap at this point or become cranky. Adults can nap for an hour or so at this point, too, if they let themselves (as is routine in siesta cultures); if not, they will still probably take a relaxing break from whatever work they are doing. Even if you don’t nap, you’ll begin to feel more alert as you move past this midday dip, and you will soon be wide awake again. (If you usually stay up relatively late at night, the dip may not actually hit until after dinner.)
In the evening, during the few hours before the start of your sleep phase, you enter the forbidden zone for sleep, an especially interesting period in which sleep is nearly impossible. If you tested your ability to nap at various times of the day, you would find it the most difficult to fall asleep during these evening hours: on the contrary, at those times you feel more awake, alert, and focused than ever. The same applies to your child. In fact, awareness of the forbidden zone turns out to be critical for understanding and treating certain common sleep problems in children.
All parents see the effects of the forbidden zone on children, though they may not understand what they are seeing. When your child seems sleepy in the afternoon or around dinnertime but gets a surprising second wind just when you want to send her to bed, it might seem strange. This is the forbidden zone at work: the longest period of sustained wakefulness occurs at the end of the day, not in the morning—that is, before, not after, the longest period of sleep. That is why your child seems so energetic all of a sudden, ready for fun or just about anything except going to bed. Even in a four-month-old who naps three times a day, the evening nap is the shortest and will be the next one to be dropped altogether.
Why is this so? Don’t we get sleepier the longer we stay awake and less able to stay asleep the longer we do sleep? We do, in part, and this effect is caused by the so-called homeostatic drive, one of the two main factors influencing sleepiness and alertness. If that were the only cause of sleepiness, we would get progressively sleepy across the day, and the drive to sleep would decrease progressively while we sleep at night. We would have trouble staying awake until dinnertime and difficulty staying asleep until morning. Since we exhibit neither of these patterns—and, in fact, we can function reasonably well during the day after getting no sleep at all the night before—there must be other causes of increasing and decreasing sleepiness across the day and night.
The other major influence is the circadian drive, a direct effect of the biological clock. The circadian system works in opposition to the homeostatic drive, trying to make us more wakeful as the day progresses and sleepier as the night goes on. The balance between the two enables us to function at fairly consistent levels all day and sleep fairly well all night (see Figure 9). However, near the end of the day the wakeful component of the circadian system temporarily dominates, causing the forbidden zone or second wind. (As we saw before, the circadian drive is so strong that it can overcome the homeostatic drive and keep you alert during the day even after a full night without any sleep.) At the start of the sleep phase, the circadian system switches to “sleep” mode; now that both systems are working in concert, pushing us toward sleep, it becomes hard to stay awake.
Other factors also affect sleepiness and alertness. Age and developmental level, more than anything else, determine one’s nighttime sleep requirement and the number of consecutive hours one can remain awake. (That is why an infant needs several naps during the day, while an older child or adult needs fewer or none.) Losing sleep night after night builds up a “sleep debt,” which essentially enhances the homeostatic drive so that the level of alertness is lowered over the whole day. Napping during the day does the opposite, removing some of the drive to sleep. That allows young children to make it through the day, but it also makes it easier to stay up late and more difficult to fall asleep at night, especially for older children and adolescents. Medication can increase the drive to sleep (sedatives and antihistamines, for example) or the drive to stay awake (coffee and other stimulants). Illness can have similar effects: fever usually makes you sleepy, pain usually keeps you awake. Psychological and cognitive factors affect sleep, too: depression sometimes increases sleepiness, especially in children, while anxiety can interfere with the ability to fall asleep.
FIGURE 9. SLEEPINESS AND ALERTNESS ACROSS THE DAY AND NIGHT—HOMEOSTATIC AND CIRCADIAN DRIVES
Setting the Biological Clock:
How Do You Know What Time Zone
You Are In?
Recall that exposure to light sets your biological clock and adjusts the timing of your sleep phase. Bright light near bedtime delays your sleep phase, so that you fall asleep later and wake (spontaneously) later. Bright light in the morning has the opposite effect, causing you to wake earlier and fall asleep earlier. If you are exposed to bright light within your sleep phase—that is, after you would usually fall asleep or before you would usually wake spontaneously—its effects are especially strong. (Exactly what happens depends on the timing, intensity, and duration of the light exposure.)
For example, suppose your current sleep phase runs from 9:00 P.M. to 6:00 A.M. Now imagine that you begin staying up until midnight every night, sitting in front of a bank of bright lights from 9:00 on. Also imagine that you put on a blindfold when you go to bed and wear it until 9:00 in the morning. You are now getting three extra hours of light at night and three extra hours of darkness in the morning. Over the next several days, your sleep phase will delay—move later—by those same three hours. Soon you will be unable to fall asleep until midnight, and you will not wake spontaneously until 9:00 in the morning. In effect, that is precisely what happens when you travel from New York to Los Angeles, cross three time zones, and get exposed to evening and morning light three hours later than you’re used to.
Now consider the opposite experiment: this time you wear the blindfold from 6:00 to 9:00 in the evening, and get up at 3:00 in the morning to sit in front of bright lights for three hours. Now the nighttime darkness starts three hours earlier than you’re used to, and so does the light in the early morning. Within a few days, your sleep phase will advance—move earlier—by those three hours. Soon you will be falling asleep at 6:00 P.M. and waking at 3:00 A.M. This type of change, of course, is what happens when you travel from Los Angeles to New York.
Actually, your biological clock normally undergoes small adjustments of this kind every day. As we saw earlier in this chapter, our circadian clocks naturally run slow: left alone, they will run on a cycle about ten minutes longer than a true twenty-four hours; in practice the cycle is closer to twenty-five hours, probably because we are regularly exposed to electric lights after the sun goes down—not as bright as sunlight, but still bright enough to have an effect—and not exposed to light while we sleep (indoors) in the morning. The result is that we have a tendency to go to sleep and wake up almost an hour later every day. In fact, many of us do just that on weekends and while on vacation. Come Sunday night or the end of a vacation, it’s difficult to go to sleep at our usual weekday time, and the next morning it’s harder than ever to get up for work or school.
So why doesn’t our sleep schedule constantly drift later and later? It’s because most days, like it or not, we have to get up at the same early time, and when we do, we are exposed to light. That morning light pushes our schedule earlier, usually enough, or almost enough, to counteract the drifting tendency. It keeps us running in place. But when we’re free to sleep late every day (as a toddler may be), or even just on weekends and vacations, we do start to drift. As we will see later in the book, this drifting is behind one of the most commonly seen sleep problems.
Are You a Lark or an Owl?
In any discussion of sleep schedules, it’s important to take individual factors into account. The forbidden zone seems very powerful for some, less so for others. This difference may be explainable in part by the traits of morning and evening preference, which divide people into the types known as “larks” and “owls.”
Owls are people who get energized at night. Their second wind is strong, and the late night is often the most pleasant time of their whole day. Owls feel most alert at that time; they can think clearly, study effectively, and play well. Staying up late is easy for them. But owls have a problem in the morning: waking up and starting the day, even after a full night’s sleep, is painful and difficult, like climbing out of a deep hole. Owls don’t like to get up, and they avoid early-morning activities whenever they can. It’s easy for an owl to become phase-delayed (as discussed in Chapter 10).
For larks, the second wind is less forceful. As night falls, larks feel as if they are sliding into the same deep hole that owls wake up from each morning. Finding it unpleasant to stay up late, larks may pass up evening activities or leave them early. But they wake up without any trouble early in the morning, usually feeling great. They want to get right up and start doing things. For larks, morning is the best time of the day and evening is the worst. They are less likely than owls to develop a phase delay; on the contrary, their sleep phase may be earlier—more advanced—than they (or their parents) desire (see Chapter 10).
People do not necessarily fall entirely into either of these categories, but most have a tendency in one direction or the other, and in many the preference is quite strong. Although this is an innate preference that does not change over time and cannot be taught, owls can follow an early schedule, and larks a late one, if circumstances demand it—albeit probably not happily. In fact, larks and owls show genuine biological differences; for example, in owls, body temperature reaches its lowest point of the night nearer the time of morning waking than it does in larks. A specific gene has even been associated with the lark trait.
“Larkness” and “owlness” exist as traits even in young children. A toddler who is an owl is especially energetic at night. She wants to be part of anything going on anywhere. She can stay up later than usual without difficulty. If her bedtime isn’t pleasant, or if its timing is not enforced regularly, the entire process of going to bed may deteriorate and her schedule may become delayed or grow variable and unpredictable. The one problem she is unlikely to have is that of early wakings.
A toddler who is a lark, on the other hand, will probably like going to sleep early. If for some reason you don’t put her to bed on time, she may grab her teddy bear and go to sleep on her own at bedtime, wherever she happens to be and regardless of anything going on around her. Bedtime for such a child is unlikely to be a problem, but she may be wide awake and ready to go at five o’clock in the morning.
Society, Sleep Deprivation,
and the Adolescent
We live in a sleep-deprived and phase-delayed culture. From adolescence until retirement, few people get enough sleep. How many of us wake up in the morning because we’ve slept enough? How many of us can get up on time without an alarm or someone waking us? How many people would not sleep later if they could? How many don’t sleep later on weekends and on vacation than they do on workdays or school days?
The reasons for our cultural sleep deprivation are complex, and there are no easy solutions. First of all, we are exposed to light for several hours between sunset and bedtime. Morning sunlight works to keep us from drifting, but it can’t always completely cancel out the effect of all that artificial light we get at nighttime. If we are also chronically sleep deprived, though—if we stay up too late and always get up earlier than we would like—the combination of morning light and sleep deprivation can be just enough to counteract the phase-delaying effect of the evening light. This pattern is usually not seen before adolescence, since that is when youngsters first gain the freedom and ability to stay up late.
Second, the electronic world continues nonstop, day and night. The days are long gone when the only thing on television from late evening till morning was a test pattern. Shows aimed at adolescents and young adults continue until the early morning hours. Teenagers give up sleep for the shows they enjoy. (Younger children will also give up sleep for television, but more often at the other end of the night, getting up early to watch cartoons.) The Internet is always on, video games are always available, and the telephone always works. Nowadays all of these activities are accessible no matter where you live; in many places restaurants, bars, movies, and arcades stay open very late as well.
Third, sleep is not a high priority for most people: when faced with a choice between sleep and another activity, most will choose the other activity. It is ingrained in our culture that you should be able to get by on little sleep most of the time and catch up occasionally. It’s a rare adolescent who willingly leaves her friends at nine o’clock to go home and sleep. (Not many adults do, either.) Conscientious adolescents may feel that it is more important to finish their homework than to go to sleep early, and most of their parents and teachers would agree.
People wrongly believe that even when they are tired their abilities to work, learn, and drive are unimpaired. Study after study has shown otherwise; yet, though most people understand that it is unsafe to drink and drive, few realize that driving under the influence of sleep deprivation can be just as dangerous. (When is the last time you handed over your car keys because you got only six hours’ sleep the night before?) The news is full of stories about teenagers whose lives were lost when they fell asleep at the wheel and drifted into oncoming traffic or continued straight when the road curved. More teenagers die in car accidents than from any other cause. In the United States, more than 100,000 car accidents and 1,500 deaths each year occur because of drowsy driving, and most single-vehicle accidents not caused by alcohol are due to lack of sleep. The drivers in about half of these accidents are teenage boys or young men. Furthermore, the effects of alcohol and sleep deprivation are cumulative: just one beer can have a devastating effect on a seventeen-year-old who has slept only five hours.
Adolescence in our culture is a recipe for sleep-schedule problems and sleep deprivation. Even without taking cultural factors into account, adolescents’ nighttime sleep is shallower and less restorative than the sleep of younger children, and the ability to nap during the day comes back. Thus, even under the best of conditions, a teenager is sleepier in the daytime than she was as a child. At the same time, she is better able to fight off sleep and stay up late. She also develops the ability to “oversleep,” that is, to sleep longer at one stretch than she really needs, or at least to repeatedly return to sleep until the late morning or into the afternoon. (Preteens generally get the amount of sleep they need and then get up.) Finally, some evidence suggests that adolescents have an inherent sleep-phase delay: they naturally fall asleep and wake later in the day, relative to light exposure, than younger children do.
Compounding the problem, in most places high school starts earlier than elementary and middle school. In some areas, students who take the bus have to get up as early as 5:30 A.M. To get the usual requirement of nine hours’ sleep, they would have to be asleep by 8:30 P.M. I find it is pointless even to suggest that idea to most sixteen-year-olds.
In short, adolescents often stay up late and get up early during the week, and they become chronically sleep deprived over time. On Fridays and Saturdays they stay up later than on weeknights, and they sleep late the next morning to make up some of their previously lost sleep. That increases the phase delay, so during the next week they fall asleep even later, get less sleep, and have more difficulty getting up in the morning for school than before. Because they are now further behind in their sleep, they sleep still later on the next weekend. As the cycle continues, the discrepancies between weeknights and weekends become more and more pronounced. A teenager may be falling asleep at 1:00 A.M. during the week and getting up at 6:00 A.M. for school after five hours of sleep or less, while on weekends she may sleep from 2:00 or 3:00 A.M. until noon or later, getting ten to fourteen hours of sleep. The amount of sleep teenagers get can easily double on the weekend, and they may get up more than six hours later then than during the week.
When a youngster’s natural wake-up time is noon, as may be the case if she sleeps till then on weekends, then not only does she go to school badly sleep deprived, but most of her class time falls at hours when her body’s physiological functions are still set for sleep. Her ability to pay attention, learn, think, and retain information is severely compromised. Since a teenager who has to be awake by six in the morning is hard-pressed to get enough sleep at night, at least in our culture, a reasonable remedy would appear to be starting the high school day later; and, at this writing, initial results of research being conducted to test that hypothesis suggests such changes are beneficial. But although a later starting time is almost certainly a good idea, at best it will only help partially. It won’t change the underlying problems.
I see no easy way to combat all the social forces that make sleep deprivation so common in adolescents. Education can help: we must recognize the importance of sleep and be willing to arrange our schedules to allow for it. It may not be possible to keep a teenage child on a perfect schedule, but by helping her to understand the impact her schedule has on her sleep and on her daytime performance, we may be able to minimize the problems. I’ve worked successfully with many teenagers using that approach. When a teenager is receptive—not all of them are—we can help her to cut down the weeknight-to-weekend sleep differential, to fall asleep earlier on school days, and in general to feel better, function better, and be happier during the week.
These days our culture prizes physical fitness and health, and much energy is devoted to diet and exercise (even when it means getting up early and sacrificing sleep to go running). If we valued proper sleep as an equally important component of well-being, we would be moving in the right direction.
Specific Sleep Problems Affecting
Different Parts of the Sleep Cycle:
When we refer to a “sleep schedule problem,” we may mean either a specific symptom (such as early-morning wakings) or the responsible underlying physiological problem (such as a sleep phase shift). In the three chapters that follow, we will look at the various types of schedule problems in detail. But keep in mind that problems discussed elsewhere in this book also may primarily affect specific parts of the sleep cycle. Therefore, before we begin, it may be useful to first see an overview of the main causes of all common sleep problems that affect the various parts of the sleep cycle, with reference to the chapters where each problem is discussed.
FIGURE 10. COMMON CAUSES OF SLEEP PROBLEMS AT DIFFERENT TIMES OF THE DAY AND NIGHT
1. Inappropriate sleep-onset associations (Chapter 4).
2. Limit-setting problems (Chapter 5).
3. Anxiety (Chapter 7).
4. Colic (Chapter 8).
5. Late sleep phase (Chapter 10).
6. Time in bed is too long (Chapter 11).
7. Short sleep requirement (Chapter 11).
8. Last nap is too late (Chapter 12).
9. Excessive napping (leading to short nighttime sleep) (Chapters 11, 12).
10. Irregular sleep-wake schedule (Chapter 11).
11. Evening noise and activity (Chapter 11).
12. Evening television (causing children to give up sleep) (Chapters 5, 11).
1. Inappropriate sleep-onset associations (Chapter 4).
2. Excessive nighttime feeding (Chapter 6).
3. Limit-setting problems (Chapter 5).
4. Anxiety (Chapter 7).
5. Medical disorders (Chapters 8, 17).
6. Sleep terrors, confusional arousals, sleepwalking, nightmares, and bedwetting (Chapters 13, 14, 15).
7. Time in bed is too long (Chapter 11).
8. Short sleep requirement (Chapter 11).
9. Excessive or too frequent napping (leading to short or fragmented nighttime sleep) (Chapters 11, 12).
10. Irregular sleep-wake schedule (Chapter 11).
11. Nighttime noise and activity (Chapter 11).
12. Nighttime television (Chapters 5, 11).
1. Early sleep phase (Chapter 10).
2. Time in bed is too long (Chapter 11).
3. Early feedings (leading to early hunger) (Chapters 6, 10).
4. Early-morning nap (interfering with the last stretch of nighttime sleep) (Chapters 10, 12).
5. Excessive napping (leading to short nighttime sleep) (Chapter 12).
6. Irregular sleep-wake schedule (Chapter 11).
7. Short sleep requirement (Chapter 11).
8. Morning light, noise, activity (Chapter 11).
9. Morning television (causing children to give up sleep) (Chapter 11).
1. Too much sleep at night (Chapter 12).
2. Short sleep requirement (Chapter 11).
3. Too many naps or “naplets” (Chapter 12).
4. Drifting/splitting naps (Chapter 12).
5. Interrupted naps (noise and stimulation) (Chapter 12).
6. Inappropriate sleep-onset associations (Chapter 4).