Pacific Sleep Program

Sleep: You can't live without it

The body falls into sleep when the urge to do so becomes relatively irresistible. It is an actively induced, regularly recurring behavioral state in which the body becomes relatively unresponsive to environmental or outside stimulation. Sleep appears essential for growth and physical repair, for memory consolidation and learning, and for processing the emotional experiences of the day. It is essential to maintaining an alert state during normal waking hours.

Though a remarkable amount is unknown about the purpose of sleep, some things are clear. Insufficient amounts or poor quality sleep are clearly associated with poor concentration and memory, emotional disturbances, incoordination, slow reaction times, accidents, judgement errors, just to name a few. The Challenger, Three Mile Island, Exxon Valdez are all names whose associated disasters are intimately linked to the effects of sleep disturbances.

Sleep Centers in the Brain

Sleep is not a passive state to be considered the simple opposite or lack of being awake. On the contrary it is actively induced and controlled. It is actually an ever changing, dynamic state. Sleep emerges as the result of the activity of cells in the 'primitive', non-thinking portions of the brain termed the brainstem and hypothalamus. These cells are organized into groups termed nuclei; they connect with each other, other parts of the brain and spinal cord in an extraordinarily complex manner. Names such as locus coeruleus, dorsal raphe nuclei, among others are well known to researchers.

Nerve cells transmit their signals by means of electrochemical activity down the long fibers of nerve cells termed axons. However, the communication between nerve cells and the information being sent is actually accomplished by chemicals produced at the end of these fibers, termed neurotransmitters. A wide range of such messenger chemicals have been intimately linked to sleep. Serotonin, norepinepherine, acetylcholine, and hypocretin are the principal ones, but they are only a few representatives of a rather wide array of transmitters.

Although considerable progress has been made in understanding how these elements work together, it is also clear we are just beginning to understand sleep control complexities.

Sleep Stages: All sleep is not equal

Sleep is objectively identified by the pattern of electrical activity generated by millions of brain cells. This activity can be recorded by small sensors placed on the scalp. These electrodes pick up the EEG, electroencephalographic, 'signal' activity which is then recorded on special equipment. Other important physical features such as muscle tone and eye movements are essential for classifying sleep and are similarly painlessly recorded.

Sleep is highly organized and is divided first into two main categories, rapid eye movement or REM sleep and non-REM or NREM sleep. These two states differ greatly. NREM sleep is further divided into four stages, numbered 1 to 4. The lowest level of wakefulness is dominated by a brain frequency pattern termed alpha rhythm, and is a highly relaxed conscious state. This gives way to Stage 1 sleep; this is light sleep. The brain has slowed to an EEG pattern termed 'theta and vertex sharp waves', and is accompanied by slow unconscious eye movements and moderate muscle relaxation. This makes up about 5% of the night. There is a certain amount of mentation present. Arousal to full alertness occurs easily, especially if the stimulus is potentially important.

This soon changes to the EEG patterns of Stage 2, 'K complexes and sleep spindles'. Muscle tone decreases further and eye movements cease. There is little response to outside stimulation; this stage should be seen as the mid level of sleep, making up approximately 50% of the night. The K complex tends to appear with a stimulus, say an outside noise. Sleep spindles may be more indicative of sounder sleep; many sleep inducing medications markedly increase these brain waves.

Stages 3 and 4 are recognized by the appearance of large but very slow brain activity; the EEG shows 'slow waves'. These stages comprise approximately 20% of total sleep; together they are termed 'slow wave (SWS) or deep sleep'. Muscle tone declines further. Stage 4 is the deepest level of sleep with awakening accomplished only with particular difficulty. Brief, often vague dreams occur, usually not recalled at all. Awakening from that stage is often characterized by a slight state of confusion. Growth hormone is produced during SWS, so this period has been especially linked to the restorative value of sleep.

The fifth stage of sleep is probably the best known, rapid eye movement sleep, REM sleep; comprising 20% or so of the night. The stage receives its name from the sudden eye movements that can be seen under the closed lids. Other features are essential if what is being recorded is true REM sleep. EEG patterns resemble stage 1, though there are distinct differences, such as the finding of 'sawtooth waves'.

The metabolism in the brain in REM sleep is actually relatively high. In contrast there is virtually a complete loss of muscle tone in the arms and legs, except for an occasional momentary twitch.

This profound muscle relaxation serves to prevent the individual from physically responding to the other feature of this stage, dreaming. Without this protective aspect, severe injury may occur. This muscle 'atonia' combined with an active brain gives this stage its other name, 'paradoxical sleep'. Awakening someone from this stage is the second most difficult, though spontaneous arousal by the sleeper is relatively frequent, shifting in and out of this stage. The mental activity of this stage is what we typically think of as dreams; rich, and usually visual, sequences. Whether dreams really have any deep, psychological symbolism remains unproven but is of considerable interest. The purpose of REM remains uncertain; but evidence points to important relationships to memory, emotional health, and sexuality, among others.

Sleep Cycles: The night has a rhythm

The sleep 'centers' of the brain organize the various stages into a fairly regular, periodic pattern. The typical sequence is for the individual to exhibit a gradual passage from light sleep, progressively deeper until reaching REM. This takes approximately 90 minutes to accomplish. The balance of a normal night consists of 4 to 6 similar 90 minute cycles.

The earliest cycles tend to have the largest amounts of slow wave sleep, which gradually decreases until being largely absent from the final cycles. Sleep disturbances associated with SWS, such as night terrors, are thus more likely to be seen during the early cycles of the night. In sharp contrast each cycle typically exhibits longer and longer periods of REM sleep. This helps to explain why the chances of awakening from a dream, or having a nightmare, are much greater the later part of the night.

Sleep Disorders Medicine

This is medicine's newest specialty, devoted to the study and treatment of sleep disorders. Its main professional organization is the American Academy of Sleep Medicine. It is responsible for the accreditation of the growing number of sleep disorder centers, to ensure that patients can feel confident that care in a certified center is of the highest quality. The American Board of Sleep Medicine is responsible for the certification of physicians wishing to be designated as specialists in the field. A variety of other research organizations focus on sleep and its disorders. The importance of this field is receiving ever-widening recognition at all levels of government and industry alike.

Circadian Rhythms: The body has a timer

The lives of all human beings obviously are organized around the 24 hour solar day. The term usually applied to this rhythm is circadian, which means 'about a day'. As it turns out, each person's biological clock keeps their sleep and wake schedule synchronized, so called entrained, to the 24 hour light-dark cycle. If a person is placed in 'temporal' isolation, completely unaware of whether it is day or night, humans sleep and wake on a 'biological day' which is about 25 hours in duration. To stay " in synch", the circadian clock essentially advances the lights out about 1 hour earlier each and every day. In normal situations, rest and activity follow body temperature. People normally retire as body temperature is falling, which it continues to do until the early AM, rising again in preparation for awakening in the morning.

This particular internal clock has been found to be located in what are termed the suprachiasmatic nuclei; strategically located in the front portion of the base of the brain, not far behind the eyes, in an area termed the hypothalamus. In fact the 'SCN' is connected to the eyes by special nerve fibers, the retinohypothalamic tract. This provides these key brain structures with powerful light inputs. Light is the most important of all the many time cues or 'zeitgebers' that keep the individual synchronized to the light-dark cycle. By a series of other nerve fiber connections, the SCN controls the production of the hormone melatonin by the small structure in the brain, the pineal gland. This hormone begins to appear as darkness nears, rising through the night to peak in the early morning hours and declining again to the usual minimal daylight levels by dawn. Its appearance is one of the best ways of "telling what time it is" in the brain, currently of great importance in sleep research and likely will also be so in the evaluation of circadian rhythm disorders.

The nature of the circadian clock is the basis for jet lag, in which the flight across times zones, especially going east, leaves the brain temporarily out of alignment with the new location. Human circadian physiology is also at the heart of problems with sleep and, even more importantly alertness, seen in shift work. This very primitive rhythm is very slow to adapt, physiologically incapable of keeping pace with the rapid time changes seen in such circumstances.

It is essential to emphasize that to be normally alert, a person must not only obtain a sufficient amount and quality of sleep, but must obtain that sleep at the appropriate time and be active when the biological clock is generating its wakefulness message. You also need to remember that a person's estimate of the amount of sleep can be very inaccurate, especially when the quality is poor.

Sleep Amounts: 5 hours is not enough

There is no single normal amount of sleep. Each person has a genetically determined amount of sleep that must be obtained to be normally alert. The range of sleep in adults is generally between 6 and 9 hours, but usually 7 to 8 is most common. It has been theorized that there is a minimum amount, termed core sleep, that is essential for basic function, 4 to 5 hours in amount and dominated by slow wave sleep. However, the predominant consensus is that this is by no means sufficient to provide normal, or safe levels of alertness.

There are scientific means of determining what an individual's requirement is, but these are complex and impractical outside of a research setting. A reasonable method for making your own such determination is to figure out how much sleep allows you to feel awake throughout the day without struggling to remain so, even when engaged in quiet activity. Amounts below 4 hours and above 10 hours have especially been associated with significantly reduced health.

An adequate sleep quantity should provide you with the alertness sufficient to operate at peak efficiency. Humans obviously can function relatively acceptably at sub optimal sleep levels. But even modest sleep reduction causes the build-up of what has come to be called a sleep debt - one which must be paid one way or the other - either by an increase in sleep or with impaired function, potentially dangerously so. Sleep amounts below 5 hours are of particular concern; people at these levels showing rather dramatic levels of sleep deprivation caused impairment.

Movement during Sleep

You are not paralyzed during sleep - well, not most of the night.

Muscle tone and physical activity progressively decrease the deeper into sleep ones goes. As discussed above, there is a complete loss of muscle tone during REM sleep. However, random brief twitches are common, even in REM sleep.

There is significant physical activity even in normal sleep. Virtually everyone has experienced a brief jerk as they drift into sleep. These are termed sleep starts or hypnic jerks, and are entirely normal.

Major adjustments in body positioning occur at least once to twice per hour. Smaller or fine movements, such as a finger or foot, often produce momentary arousals (brief breaks in the normal continuity or passage of sleep) and can be perfectly normal at 10 or so times per hour of sleep. Even people who say they don't move all night make these same adjustments; they simply aren't encoded in memory. In fact, if the rate and amount of movement drops below normal, a person wakes in the morning feeling poorly refreshed, stiff, aching.

If you seem to exhibit a great deal of movement during your sleep, then you should explore the possibility that you may have an actual sleep disorder.

Naps

The physiology of the 'Siesta' Our culture tends to view a nap almost as a sign of weakness of character or laziness. Other cultures incorporate a nap into their daily routine. All ages and species nap. Western society's view of the nap is yet another reflection of the lack of appreciation of the importance of sleep to alertness.

One of the first issues to try and settle is what actually is a nap? It turns out that what may be defined as a nap may be sleep lasting just a few minutes or as long as many hours - but certainly less than half the main sleep period. It is also important to try and identify when to consider a nap as abnormal. In general a normal nap is relatively voluntary or elective; it is not overwhelming or irresistible.

Early in childhood sleep changes from a pattern of frequent, variable length sleep and wake periods to one in which sleep is consolidated at night. There is a clear indication that napping increases again from middle age on, but not necessarily daily. People who nap regularly do not appear to do so because they have a sleep disorder, though people who do are more inclined to fall asleep during the day. Habitual nappers don't have a different personality than those who don't nap.

The period from roughly 1PM to 4PM shows the greatest tendency for people to nap. Though there is strong popular view that afternoon sleepiness is related to meals, especially ones rich in carbohydrates, the bulk of evidence shows this not to be true, in general, though it may have some influence in certain individuals. In fact, it is now clear that the tendency to be sleepy and nap then is due to the body's genetically determined sleep-wake rhythm. There is a biphasic tendency to sleep, afternoon and night. It has been theorized that the midday nap evolved in order to conserve energy and water during the hottest time of the day. The morning and evening, in contrast, are alert periods with little inclination to sleep, the latter sometimes referred to as the "forbidden zone" for sleep.

Napping should be viewed as normal - in fact, encouraged, if it improves alertness, and is especially valuable if sleep the night before was short. There don't appear to be any negative effects, with two exceptions. The first likely comes from the tendency to go into SWS in the afternoon. Awakening from prolonged naps at that time can be accompanied by a groggy, even confused state termed sleep inertia, usually lasting up to 15 minutes. The other is that prolonged naps, especially over 2 hours long, may reduce nighttime sleep. It is best to keep naps to no longer than 20 to 30 minutes, and recognize that even a 5-minute 'snooze' may be beneficial.

Feeling Rested: It really is possible

Feeling rested encompasses a number of physical and mental qualities, the latter involving both alertness and mood aspects. Alertness has a 60 to 90 minute variation or cycle. Fatigue should be expected to be experienced as the day progresses.

In order to feel normally alert; sleep should be of normal quality, each person's genetically determined amount should be obtained on a daily basis, and should occur at the same time each day according to each person's also genetically determined circadian rhythm. A voluntary nap should enhance the quality of the hours otherwise devoted to awake activity.

The "Maturing" Sleep System

Sleep changes substantially from birth on into one's senior years. In infancy sleep can reach 16 hours, half of which is spent in REM. The adult proportion of around 20% REM is reached around age 3. Children spend a large proportion of their night in very deep SWS; this accounts for why it may be so difficult to awaken a sleeping child. This may also be relevant to children's tendency to exhibit what are termed 'SWS parasomnias', such as night terrors.

Adolescents exhibit a substantial decline in SWS, which continues on into adult life. Sleep in adolescence remains very sound, however. They exhibit a delay in their circadian rhythm, explaining the apparent sudden shift to staying up late. Unfortunately, the sleep requirement doesn't decrease at the same time. With the early start times for most schools, the adolescent ends up with chronic sleep loss, explaining their sleepy reputation as well as sleeping in remarkably late on weekends.

Adults have a fairly stable sleep structure except for the decline in SWS. Awakenings from sleep become increasingly common, especially after age 45. Many of the physical disorders affecting sleep are seen with increasing frequency, especially after age 30 to 40. There is a decrease in the flexibility of the circadian clock, likely one of the factors accounting for the intolerance to shift work which often begins to be problematic in the 40s, as well.

Sleep in seniors is especially disturbed, with increasingly frequent arousals and awakenings, even in normal people. These changes occur even when you take into account such things as arthritis or prostrate enlargement causing nighttime urination. Seniors may have little, if any SWS. The amount of REM is little changed. Circadian rhythms change in seniors, with an increasing tendency to show an advanced sleep phase, producing the picture of the senior falling asleep in early evening. This has especially been seen in aged men. This may correlate to the decrease in melatonin production usually seen.

Sleep Hygiene: More sound rules to live by

There are a number of things which may be done to improve the quantity and quality of sleep, and to help find relief for insomnia or prevent the development of chronic insomnia. A list of some of those follows:

Evenings should be relaxed, especially within 2 hours of lights out.
The bedroom should be reserved for sleep. Plan your sexual activity according to how it usually affects your alertness. Things typically done while awake should not be done in the bedroom.
Nighttime rituals can be very useful; this may include reading or television if these activities are relaxing and typically sleep-promoting.
Do not watch the clock to check how much time has passed. If you have trouble either falling asleep or returning to sleep, take a break from the frustrated, worried feelings often present after about 30 minutes has passed. Leave the bedroom and go do something quiet and relaxing such as listening to monotonous music. DO NOT do things which are productive, involved, or entertaining.
If your mind is racing and you can't stop thinking of certain issues, jot down a few brief notes and review them in the morning or at some other designated time. The same thing applies to problems getting back to sleep after an awakening.
Lights out should be at the same time, seven days per week.
Exercise regularly, daily if possible, for 30 minutes aerobically but not within 4 to 6 hours of bedtime.
Diet modification may be beneficial. Avoid large meals late at night. They tend to produce difficulty getting to sleep or staying so. Heartburn or what is termed gastroesophageal relux is much more apt to occur after large meals eaten in the late evening. Avoid fatty or spicy foods. If stomach discomfort or abdominal bloating or gas is a problem, try and avoid the offending foods.
The bedroom should be cool. Room or ambient temperatures above 75° should be avoided; sleep clearly deteriorates showing a decrease in the deep stages of sleep and an increase in the number of awakenings. Also, take care to avoid excessively high heating blanket settings if you must use one.
The bedroom should also be reasonably quiet. However, there is a remarkable variation in how sensitive one person is to outside noise versus another. The more irregular as well as how loud the sound, or how significant (a baby crying); the greater the likely impact on sleep onset or maintenance. The use of a small fan can be helpful; its monotonous sound can be relaxing plus it can block out or mask irritating noises.
The kind of mattress or sleeping surface is important but far less so than you may have been led to believe. A good quality, firm mattress is best. Waterbeds should be 'waveless'. People are able to sleep on a remarkably diverse array of sleeping surfaces, apparently equally well. However, individuals with low back pain may do better on a firm mattress. Our research has shown that a high quality adjustable air system bed appears to be the best for individuals with chronic low back pain that adversely affects their sleep. It important to also recognize that sleeping with someone else in a small bed is associated with poor sleep, including lower levels of REM and SWS.
The pillow selected may be much more important to sleep than the mattress. It can be a very individual item. Some people will do best to take their regular pillow with them when they travel. Special pillows may be needed in individuals with neck pain.
Caffeine can have a substantial, negative effect on the ability to get to sleep and/or stay asleep. Avoiding caffeine after noon is best. For the individual who is especially sensitive, problems may occur even with a single cup in the morning. Remember, 'decaf' still has caffeine. Watch for it in unexpected places, for example, some orange juices. Also remember many soft drinks are high in caffeine, as are regular teas. Chocolate (sigh) has stimulating compounds and can also disturb sleep.
Alcohol is often used as a self-medication for sleep. Unfortunately, this turns out to be a poor choice. Tolerance develops so that the "dose" must be increased. Though rapidly acting, it wears off quickly during the night and produces awakenings as a result, sometimes unpleasant dreaming. It may also be frankly dangerous if you have sleep apnea, as it relaxes the throat muscles and depresses the brain's breathing control centers. You can figure that you will metabolize or "burn off" about one drink per hour, so plan your intake and lights out accordingly.
Nicotine also disturbs sleep, in much the same way as caffeine. Its best to avoid it for many health reasons. Improving sleep quality should be included on the growing list of reasons to quit. Remember, nicotine, no matter what the source, has the same effect. Certainly, avoid it within 3 to 4 hours of going to bed.

Sleep Disorders

Sleep related problems and the disorders of the sleep and wake processes are extraordinarily common. Though the affected individual can be keenly aware of a problem, they may be wholly unaware of a connection between symptoms and the underlying cause. The majority of people have little real information about sleep problems. This, unfortunately, often includes one's own doctor. All this makes it difficult to provide accurate statistics. The National Sleep Foundation has been conducting scientific polls that have helped substantially understand the scope of the problem.

Only about 1/3 of adults receive the recommended amount of sleep per night. Over 10% have frequent difficulty falling asleep. Roughly 1/5 adults have abnormally fragmented sleep. In a recent latest poll 44% of men, especially ages 30 to 64, and 36% of women snored frequently. 16% of men and 10% of women report pauses in their breathing during the night, suggesting they could have sleep apnea. 18% reported daytime sleepiness enough to interfere with daily activities several times per week. Nearly 1/3 have dozed off at the wheel in the past year. Fatigue is involved in more accidents than either alcohol or drugs.

Weight

Weight and Sleep Disorders
Description: Excessive weight is an extraordinarily prevalent problem in our society; with a wide range of associated social, scientific, and medical effects. Overweight is a term used to indicate an increase in body weight above a certain set level, which may or may not be significant in terms of health. An athlete may have "excess weight" from an increase in muscle mass but certainly wouldn't be necessarily considered abnormal. Obesity is an abnormal level of accumulated body fat. Its importance lies in its association with numerous serious disorders; including diabetes, high blood pressure, heart disease, stroke, just to name a few. There is a very strong association between excess weight and the severity of sleep apnea, though it is rarely the actual cause of it. It has been recently discovered that sleep apnea itself interferes with metabolism, enhancing further weight gain.

Evaluation: There are three main ways to measure obesity. The least accurate is relative weight, the actual body weight divided by a standard weight based upon height. The most complex is using one of the various measures of body fat; normal % body fat is 10% to 20% for adult males, and 17% to 25% for adult women. The most generally useful method is the Body Mass Index, or BMI, which relates the actual body weight to the squared power of the actual height. It now generally accepted that a BMI of 25 is normal, 26 to 30 is overweight, and > 30 is obese. The medical problems associated with excessive weight begin to be seen more frequently at levels of > 25, and this is true of sleep apnea as well.

Treatment: The number of different programs or methods for achieving weight loss are truly extraordinary; ranging from behavioral or self-restraint methods, to very low calorie diets (liquid supplements), to anorexiant or weight loss medications, to surgeries such as gastroplasty, to exercise combined with a reduced calorie diet. Pros and cons of each are beyond the scope of this site. In general, you are strongly encouraged to lose weight. Doing so is almost always very helpful in decreasing the severity of sleep apnea; though don't expect it to be cured, as this is quite rare. The best overall approach is a modest calorie reduction to achieve a permanent change in dietary pattern. Combined with exercise, this will help achieve your goal gradually. The latter has the added benefit of promoting better quality sleep as discussed elsewhere in this site. It is important to emphasize that you may gain a major benefit from even limited weight loss. Generally the benefit of weight reduction for sleep apnea begins when at least 5% of your baseline weight has been lost. Be patient, don't let yourself become discouraged.

Exercise - the misunderstood sleep aide

The topic of exercise and sleep is an extremely important one. Physical activity can have a substantial effect upon sleep, in the management of a wide range of sleep disorders, and sleep itself can have a significant impact on physical capabilities. People with poor sleep have often been found to be sedentary. The theory that sleep has an energy conservation function appears to be valid.

The structure of sleep changes with exercise so that an increase in deep sleep (SWS), stages 3 and 4, occurs - but mainly in those individuals who are fit and only when they exercise an adequate length of time, around 30 minutes, and consistently. Flexibility and stretching exercise alone are not adequate to improve sleep quality. An increase in growth hormone, essential for the body's reparative processes, occurs during SWS sleep.
Exercise must be timed so that it's not too close to bedtime, as it will produce an alerting effect, delaying sleep onset as well as affecting its depth. That obtained in the afternoon has the most beneficial overall effect. Prolonged high intensity exercise may produce deterioration in sleep, especially when obtained in the evening. Certain other forms of exercise can facilitate sleep in other ways, where aerobic fitness is not involved. Progressive muscular relaxation exercises as well as stretching may be of benefit through their tendency to reduce anxiety.

Exercise has a generally alerting, sense of well-being enhancing effect. Physical activity may overcome the negative effects of sleep loss - but only briefly and only partially. However, exercise cannot really combat or overcome the true effect of sleep loss.