Sleep disorders

Definition

Sleep disorders are a group of syndromes characterized by disturbance in the individual's amount of sleep, quality or timing of sleep, or in behaviors or physiological conditions associated with sleep.

Description

Although sleep is a basic behavior in animals as well as humans, researchers still do not completely understand all of its functions in maintaining health. Since 1975, however, laboratory studies on human volunteers have yielded information about the different types of sleep. Researchers have learned about the cyclical patterns of different types of sleep and their relationships to breathing, heart rate, brain waves, and other physical functions. These measurements are obtained by a technique called polysomnography. There are about 70 different sleep disorders. To qualify for the diagnosis of sleep disorder, the condition must be a persistent problem, cause the patient significant emotional distress, and interfere with his or her social, academic, or occupational functioning.

There are five stages of human sleep. Four stages have non-rapid eye movement (NREM) sleep, with unique brain wave patterns and physical changes occurring. Dreaming occurs in the fifth stage, during rapid eye movement (REM) sleep.

Stage one NREM sleep. This stage occurs while a child is falling asleep. It represents about 5 percent of sleep time.
Stage two NREM sleep. In this stage, (the beginning of "true" sleep), the child's electroencephalogram (EEG) will show distinctive waveforms called sleep spindles and K complexes. About 50 percent of sleep time is stage two NREM sleep.
Stages three and four NREM sleep. Also called delta or slow wave sleep, these are the deepest levels of human sleep and represent 10 to 20 percent of sleep time. They usually occur during the first 30 to 50 percent of the sleeping period.
REM sleep. REM sleep accounts for 20 to 25 percent of total sleep time. It usually begins about 90 minutes after the child falls asleep. It alternates with NREM sleep about every hour and a half throughout the night. REM periods increase in length over the course of the night.

Sleep cycles vary with a person's age. Children and adolescents have longer periods of stage three and stage four NREM sleep than do middle aged or elderly adults. Because of this difference, the doctor needs to consider the individual's age when evaluating a sleep disorder. Total REM sleep also declines with age.

The average length of nighttime sleep varies among individuals. Most people sleep between seven and nine hours a night. This population average appears to be constant throughout the world. In temperate climates, however, people often notice that sleep time varies with the seasons. It is not unusual for people in North America and Europe to sleep about 40 minutes longer per night during the winter. Infants can regularly sleep up to 16 hours a day. The total amount of sleep declines as the infant gets older. Teenagers may actually need more sleep than slightly younger children and often sleep nine or more hours a day.

Sleep disorders are classified based on what causes them. Primary sleep disorders are distinguished as those that are not caused by other mental disorders, prescription medications, substance abuse, or medical conditions. The two major categories of primary sleep disorders are the dyssomnias and the parasomnias.

Dyssomnias

Dyssomnias are primary sleep disorders in which the patient suffers from changes in the amount, restfulness, and timing of sleep. The most important dyssomnia is primary insomnia, which is defined as difficulty that lasts for at least one month in falling asleep or remaining asleep. Primary insomnia can be caused by many things, including a traumatic event related to sleep or bedtime, and it is often associated with increased physical or psychological arousal at night. Children who experience primary insomnia may develop anxiety related to not being able to sleep. The child may come to associate all sleep-related things (their bed, bedtime, etc.) with frustration, making the problem worse. The child may then becomes more stressed about not sleeping.

Hypersomnia is a condition marked by excessive sleepiness during normal waking hours. The individual has either lengthy episodes of daytime sleep or episodes of daytime sleep on a daily basis even though he or she is sleeping normally at night. In some cases, people with primary hypersomnia have difficulty waking in the morning and may appear confused or angry. This condition is sometimes called sleep drunkenness and is more common in males.

The number of people with primary hypersomnia is unknown, although 5 to 10 percent of patients in sleep disorder clinics have the disorder. Primary hypersomnia usually affects young adults between the ages of 15 and 30.

Kleine-Levin syndrome is a recurrent form of hypersomnia that usually starts in late teen years. Doctors do not know the cause of this syndrome. It is marked by excessive drowsiness and for short spells, maybe two to three days, the person sleeps 18 to 20 hours per day, overeats, and is highly irritable. Males are three or four times more likely than females to have the syndrome.

PARASOMNIAS Parasomnias are primary sleep disorders in which the individual's behavior is affected by specific sleep stages or transitions between sleeping and waking. They are sometimes described as disorders of physiological arousal during sleep.

Nightmare disorder is a parasomnia in which the child is repeatedly awakened from sleep by frightening dreams and is fully alert on awakening. The actual rate of occurrence of nightmare disorder is unknown. Approximately 10 to 50 percent of children between three and five years old have nightmares , as do many older children. The nightmares occur during REM sleep, usually in the second half of the night. The child is usually able to remember the content of the nightmare and may be afraid to go back to sleep. More females than males have this disorder, but it is not known whether the sex difference reflects a difference in occurrence or a difference in reporting. Nightmare disorder is most likely to occur in children under severe or traumatic stress.

Sleep terror disorder is a parasomnia in which the child awakens screaming or crying. The child also has physical signs of arousal, like sweating and shaking. Sleep terror is sometimes referred to as pavor nocturnus. Unlike nightmares, sleep terrors typically occur in stage three or stage four NREM sleep during the first third of the night. The child may be confused or disoriented for several minutes and cannot recall the content of the dream. He or she may fall asleep again and not remember the episode the next morning. Sleep terror disorder is most common in children four to 12 years old and is usually outgrown in adolescence . It affects about 3 percent of children. In children, more males than females have the disorder.

Sleepwalking disorder, which is sometimes called somnambulism , occurs when the child is capable of complex movements during sleep, including walking. Like sleep terror disorder, sleepwalking occurs during stage three and stage four NREM sleep during the first part of the night. If the child is awakened during a sleepwalking episode, he or she may be disoriented and have no memory of the behavior. In addition to walking around, individuals with sleepwalking disorder have been reported to eat, use the bathroom, unlock doors, or talk to others. It is estimated that 10 to 30 percent of children have at least one episode of sleepwalking. However, only 1 to 5 percent meet the criteria for sleepwalking disorder. The disorder is most common in children eight to 12 years old.

Demographics

In the United States, 20 to 25 percent of children have some kind of sleep problem. Nightmares are believed to occur in about 30 percent of children, usually in younger children. Sleepwalking occurs more than once in about 25 to 30 percent of children. The most common age group to experience sleepwalking is children under 10. Insomnia is reported to occur in approximately 23 percent of children. Many other sleep disorders occur less frequently but are still a problem for many children.

Causes and symptoms

The causes of sleep disorders vary depending on the disorder. Many times, stress, anxiety, or other factors are found to be the cause. Often the underlying cause of the sleep disorder is never found.

The most important symptoms of sleep disorders are insomnia and sleepiness during waking hours. Insomnia is by far the more common of the two symptoms. It covers a number of different patterns of sleep disturbance. These patterns include inability to fall asleep at bedtime, repeated awakening during the night, and/or inability to go back to sleep once awakened.

When to call the doctor

If a child does not seem to be getting enough sleep at night or the child wakes frequently or seems tired frequently during the day, it may be helpful to consult a doctor.

Diagnosis

Diagnosis of sleep disorders usually requires a psychological history as well as a medical history. Physical examinations are not usually revealing. The patient's sex and age are useful starting points in assessing the problem. The doctor may also talk to other family members in order to obtain information about the patient's symptoms. The family's observations are particularly important for evaluating sleepwalking, kicking in bed, snoring loudly, or other behaviors that the patient cannot remember.

Psychological testing

The doctor may use psychological tests or inventories to evaluate insomnia because it is frequently associated with mood or affective disorders. The Minnesota Multiphasic Personality Inventory (MMPI), the Millon Clinical Multiaxial Inventory (MCMI), the Beck Depression Inventory, and the Zung Depression Scale are the tests most commonly used in evaluating this symptom.

Laboratory studies

If the doctor is considering breathing-related sleep disorders, myoclonus, or narcolepsy as possible diagnoses, he or she may ask the patient to be tested in a sleep laboratory or at home with portable instruments.

POLYSOMNOGRAPHY Polysomnography can be used to help diagnose sleep disorders as well as conduct research into sleep. In some cases the patient is tested in a special sleep laboratory. The advantage of this testing is the availability and expertise of trained technologists, but it is expensive. Since 2001, however, portable equipment is available for home recording of certain specific physiological functions.

MULTIPLE SLEEP LATENCY TEST (MSLT) The multiple sleep latency test (MSLT) is frequently used to measure the severity of the patient's daytime sleepiness. The test measures sleep latency (the speed with which the patient falls asleep) during a series of planned naps during the day. The test also measures the amount of REM sleep that occurs. Two or more episodes of REM sleep under these conditions indicates narcolepsy. This test can also be used to help diagnose primary hypersomnia.

REPEATED TEST OF SUSTAINED WAKEFULNESS (RTSW) The repeated test of sustained wakefulness (RTSW) measures sleep latency by challenging the patient's ability to stay awake. In the RTSW, the patient is placed in a quiet room with dim lighting and is asked to stay awake. As with the MSLT, the testing pattern is repeated at intervals during the day.

Treatment

Treatment for a sleep disorder depends on what is causing the disorder. For example, if major depression is the cause of insomnia, then treatment of the depression with antidepressants or psychological counseling should resolve the insomnia. The use of antidepressants in minors is a matter of debate. In October 2003, the United States Food and Drug Administration issued an advisory indicating that children being treated with selective serotonin re-uptake inhibitor antidepressants (SSRIs) for major depressive illness may be at higher risk for committing suicide . A similar warning was issued in the United Kingdom. Parents and physicians must weigh the benefits and risks of prescribing these medications for children on an individual basis.

Medications

Medications for sleep disorders are generally not recommended for use by children. In most cases medications are the treatment of last resort. If children with sleep terror disorder or sleepwalking are treated with medication, then they may be given benzodiazepines because this type of medication suppresses stage three and stage four NREM sleep.

Psychotherapy

Psychotherapy is recommended for patients with sleep disorders associated with other mental disorders. In many cases the patient's scores on the Beck or Zung inventories will suggest the appropriate direction of treatment.

Sleep preparation

Children with sleep disorders such as insomnia may benefit from a regular pattern of pre-bedtime rituals designed to help the child relax and prepare for bed. Fluid intake should usually be limited in the hours before bed to reduce the need to get out of bed and use the toilet. Children should generally not be given caffeine in the evening, as it may make it harder for them to fall asleep. Children with nightmare disorder may benefit from limits on television or movies. Violent scenes or frightening science fiction stories appear to influence the frequency and intensity of children's nightmares.

Alternative treatment

Some alternative approaches may be effective in treating insomnia caused by anxiety or emotional stress. For some people, meditation practice, breathing exercises, and yoga can break the vicious cycle of sleeplessness, worry about inability to sleep, and further sleeplessness. Yoga can help some people to relax muscular tension in a direct fashion. The breathing exercises and meditation can keep some patients from obsessing about sleep.

Homeopathic practitioners recommend that people with chronic insomnia see a professional homeopath. They do, however, prescribe specific remedies for at-home treatment of temporary insomnia: Nux vomica for alcohol or substance-related insomnia, Ignatia for insomnia caused by grief, Arsenicum for insomnia caused by fear or anxiety, and Passiflora for insomnia related to mental stress.

Melatonin has also been used as an alternative treatment for sleep disorders. Melatonin is produced in the body by the pineal gland at the base of the brain. This substance is thought to be related to the body's circadian rhythms.

Practitioners of traditional Chinese medicine usually treat insomnia as a symptom of excess yang energy. Cinnabar is recommended for chronic nightmares. Either magnetic magnetite or "dragon bones" is recommended for insomnia associated with hysteria or fear. If the insomnia appears to be associated with excess yang energy arising from the liver, the practitioner will give the patient oyster shells. Acupuncture treatments can help bring about balance and facilitate sleep.

Dietary changes such as eliminating stimulant foods (coffee, cola, chocolate) and late-night meals or snacks can be effective in treating some sleep disorders. Nutritional supplementation with magnesium, as well as botanical medicines that calm the nervous system, can also be helpful. Among the botanical remedies that may be effective for sleep disorders are valerian ( Valeriana officinalis ), passionflower ( Passiflora incarnata ), and skullcap ( Scutellaria lateriflora ).

Prognosis

The prognosis depends on the specific disorder. Children usually outgrow sleep disorders. Patients with Kleine-Levin syndrome usually get better around age 40. The prognosis for sleep disorders related to many other

KEY TERMS

Apnea —The temporary absence of breathing. Sleep apnea consists of repeated episodes of temporary suspension of breathing during sleep.

Cataplexy —A symptom of narcolepsy in which there is a sudden episode of muscle weakness triggered by emotions. The muscle weakness may cause the person's knees to buckle, or the head to drop. In severe cases, the patient may become paralyzed for a few seconds to minutes.

Circadian rhythm —Any body rhythm that recurs in 24-hour cycles. The sleep-wake cycle is an example of a circadian rhythm.

Dyssomnia —A primary sleep disorder in which the patient suffers from changes in the quantity, quality, or timing of sleep.

Electroencephalogram (EEG) —A record of the tiny electrical impulses produced by the brain's activity picked up by electrodes placed on the scalp. By measuring characteristic wave patterns, the EEG can help diagnose certain conditions of the brain.

Hypersomnia —An abnormal increase of 25% or more in time spent sleeping. Individuals with hypersomnia usually have excessive daytime sleepiness.

Hypnotics —A class of drugs that are used as a sedatives and sleep aids.

Hypopnea —Shallow or excessively slow breathing usually caused by partial closure of the upper airway during sleep, leading to disruption of sleep.

Insomnia —A sleep disorder characterized by inability either to fall asleep or to stay asleep.

Jet lag —A temporary disruption of the body's sleep-wake rhythm following high-speed air travel across several time zones. Jet lag is most severe in people who have crossed eight or more time zones in 24 hours.

Kleine-Levin syndrome —A disorder that occurs primarily in young males, three or four times a year. The syndrome is marked by episodes of hypersomnia, hypersexual behavior, and excessive eating.

Narcolepsy —A life-long sleep disorder marked by four symptoms: sudden brief sleep attacks, cataplexy (a sudden loss of muscle tone usually lasting up to 30 minutes), temporary paralysis, and hallucinations. The hallucinations are associated with falling asleep or the transition from sleeping to waking.

Nocturnal myoclonus —A disorder in which the patient is awakened repeatedly during the night by cramps or twitches in the calf muscles. Also sometimes called periodic limb movement disorder.

Non-rapid eye movement (NREM) sleep —A type of sleep that differs from rapid eye movement (REM) sleep. The four stages of NREM sleep account for 75–80% of total sleeping time.

Parasomnia —A type of sleep disorder characterized by abnormal changes in behavior or body functions during sleep, specific stages of sleep, or the transition from sleeping to waking.

Pavor nocturnus —Another name for sleep terror disorder.

Polysomnography —An overnight series tests designed to evaluate a patient's basic physiological processes during sleep. Polysomnography generally includes monitoring of the patient's airflow through the nose and mouth, blood pressure, electrocardiographic activity, blood oxygen level, brain wave pattern, eye movement, and the movement of respiratory muscles and limbs

Primary sleep disorder —A sleep disorder that cannot be attributed to a medical condition, another mental disorder, or prescription medications or other substances.

Rapid eye movement (REM) latency —The amount of time it takes for the first onset of REM sleep after a person falls asleep.

Rapid eye movement (REM) sleep —A phase of sleep during which the person's eyes move rapidly beneath the lids. It accounts for 20-25% of sleep time. Dreaming occurs during REM sleep.

Restless legs syndrome (RLS) —A disorder in which the patient experiences crawling, aching, or other disagreeable sensations in the calves that can be relieved by movement. RLS is a frequent cause of difficulty falling asleep at night.

Sedative —A medication that has a calming effect and may be used to treat nervousness or restlessness. Sometimes used as a synonym for hypnotic.

Sleep latency —The amount of time that it takes to fall asleep. Sleep latency is measured in minutes and is important in diagnosing depression.

Somnambulism —Another term for sleepwalking.

conditions depends on successful treatment of the underlying problem. The prognosis for primary sleep disorders is affected by many things, including the patient's age, sex, occupation, personality characteristics, family circumstances, neighborhood environment, and similar factors.

Prevention

There is no known way to prevent sleep disorders, although having a good, regular, sleep schedule with a nighttime ritual intended to reduce stress may help.

Parental concerns

Children who do not get enough sleep, or do not get good quality sleep, may seem irritable or uncooperative during the day. Lack of sleep reduces the ability to concentrate and decreases mental functioning, so children who are not getting enough good sleep at night may have poor concentration skills and poor academic performance.

Resources

BOOKS

Kryger, Meir H., Thomas Roth, William C. Dement, eds. Principles and Practice of Sleep Medicine , 3rd ed. Philadelphia: Saunders, 2000.

Reite, Martin, John Ruddy, and Kim Nagel. Concise Guide to Evaluation and Management of Sleep Disorders , 3rd ed. Washington, DC: American Psychiatric Publishing, 2002.

ORGANIZATIONS

National Sleep Foundation. 1522 K Street, NW, Suite 500, Washington, DC 20005. Web site: http://www.sleepfoundation.org.

Tish Davidson, A.M. Rebecca J. Frey, PhD