early everyone has had the experience
of poor or insufficient sleep. Typically this altered sleep is associated with
some change in one's ability to function during the daytime. For most
individuals the change in sleep and wakefulness is voluntary, is associated with
a clearly identifiable etiology
and is time limited; therefore, it is usually of little concern to the
individual. However, for many individuals the problem is severe, chronic or of
unknown etiologyuand causes the patient to seek medical attention. Patients
seeking attention for a sleep problem typically complain of one of three types of
problems: insomnia, daytime sleepiness, or inappropriate behaviors during
sleep.
Insomnia
is the most common symptom encountered in the general population. Population
surveys indicate that between 20 and 33 percent of the population complain of
difficulty with sleep. Generally females, the elderly, and shift workers report
higher rates of insomnia than individuals in the general population (Figure 1).
Insomnia is also more common among psychiatric patients, especially those
suffering from depression. Low socioeconomic status, poor education, chronic
medical illness, recent life stress, and the use of alcohol are also associated
with an increased incidence of insomnia.
Excessive daytime sleepiness refers to an inability to stay alert during the day, or frequent sleep attacks during the day. Surveys of the general population have found that between 0.5 and 5 percent of those surveyed complain of sleepiness. Variations in the prevalence depend on the specific population sampled and the questions that are asked. Those surveys yielding rates of less than 3 percent generally are earlier studies that queried respondents regarding hypersomnia. Later studies, showing rates of 4 to 5 percent, have consisted of investigations that included more specific questions regarding excessive sleepiness during the day.
Several groups within the general population have been identified as having higher than usual rates of sleepiness. Young adults and the elderly have been shown to be sleepier than individuals in other age groups. In both of these sub-groups, the increase in sleepiness is related to the quantity and quality of nocturnal sleep. Finally, among the nearly 25 percent of the work force engaged in shift work, there is a very high rate of complaints of excessive daytime sleepiness during waking hours.
Parasomnias refer to movement and behaviors occurring during sleep. These movements are normal or abnormal if they occur during wakefulness, but they are inappropriate when they occur during sleep. The prevalence of parasomnias varies depending on the specific disorder. Several types of movements, frequently repeated in children, are associated with partial arousals from sleep. These include movements associated with sleepwalking and night terrors. These conditions often occur in conjunction with difficulty arousing from sleep, confusion on awakening, and amnesia for the event. Periodic leg movements (typically occurring during NREM sleep) and REM sleep behaviors may occur with or without an arousal and are most common in the elderly.
The diagnosis of sleep problems requires a systematic evaluation of both signs and symptoms. The first step in evaluating a patient requires taking a careful sleep, medical and psychiatric history. An assessment of medication and other drug use (e.g., alcohol or caffeine) is also important. As drug use and sleep-waking scheduling are often difficult to ascertain by history, sleep logs are often collected for a two week period. The sleep log should document the hour when the individual goes to bed and the arising time, the time taken to fall asleep, the number of awakenings, total sleep time, the timing and duration of daytime naps, as well as the types of drugs used during the day. A physical examination, appropriate clinical laboratory tests and a radiological test are then performed. All night polysomnography and the Multiple Sleep Latency Test are often performed to identify the etiology of the sleep problem as well as to determine its severity. These recording provide information about the quantity and quality of sleep (i.e., sleep fragmentation and sleep staging). They also document the presence of sleep-related pathologies such as respiratory disturbances and leg movements during sleep. The Multiple Sleep Latency Test, which consists of repeated measurements of sleep latency during the day, is used to document the degree of daytime sleepiness and the propensity for REM onset sleep (see Part K., Daytime Sleepiness and Alertness).
The complexity of the diagnostic process in dealing with sleep disorders reflects the multitude of etiologies which can lead to a sleep complaint. A sleep complaint may arise from a primary sleep disorder. That is, there may be a disorder of normative sleep physiology. The disorders of narcolepsy, obstructive sleep apnea syndrome, and REM behavior disorder are examples of primary sleep disorders. Sleep problems also may arise secondary to a disorder that occurs during wakefulness, or there may be an exacerbation of such a disorder during sleep. Insomnia secondary to depression is considered to be a secondary sleep disorder. Nocturnal asthma is an example of a waking disorder which is typically exacerbated by sleep. Drugs used to treat waking disorders can also cause sleep difficulties. For example, respiratory stimulants used to treat chronic obstructive pulmonary disease and H1 antihistamines used to treat allergies may result in complaints of insomnia and daytime sleepiness, respectively. Disruption of the sleep-waking schedule can also lead to sleep complaints. These disturbances might be externally driven (e.g., as in shift work) or be due to a dysfunction of the internal circadian pacemaker. Finally, it is important to recognize that sleep problems can be due to behavioral maladaptation. Knowledge of behavioral abnormalities are seen as critical in the evaluation of insomnia. Behavioral causes and treatments for insomnia are well documented. Similarly, a voluntary reduction of sleep is viewed as a common cause of daytime sleepiness in the general population.
Insomnia is a perception by patients that their sleep is inadequate or abnormal. This symptom includes difficulty initiating sleep, frequent awakenings during the night, a short sleep time, and nonrestorative sleep. Difficulty sleeping at night represents only part of the picture in patients with insomnia. The daytime symptoms associated with disturbed sleep are important to the patient and need to be considered. In fact, in the absence of daytime indications of poor sleep, treatment of the symptoms may not be necessary. Daytime effects such as fatigue, sleepiness, impaired daytime function, depression, anxiety, and other mood changes are often attributed by the patients to their poor sleep. Of course, patients with psychiatric disorders attribute their psychological symptoms to poor sleep. It is therefore critical to determine whether poor sleep is causing disturbed daytime function or whether a psychological disorder is primary and the sleep disturbance is secondary.
Given the large number of patients complaining of insomnia, it is not surprising that there are many responsible etiologies. Psychiatric disorders, especially depression and most chronic medical illnesses are associated with complaints of insomnia. Of the various medical disorders, respiratory conditions such as asthma and chronic obstructive lung disease have been the most widely studied. Pain can also cause sleep disturbances. Duodenal ulcer patients frequently complain of pain that awakens them during the night; it is probable that this pain is related to increases in gastric secretion, which in turn occurs during REM periods. The nocturnal pain and discomfort of arthritis and other rheumatological disorders are also frequently causes of insomnia. Similarly, the burning foot pain of the diabetic and other polyneuropathies are often worse at night. The role of primary sleep disorders and circadian rhythm disorders also need to be considered in the evaluation of an individual with insomnia.
Nocturnal gastric acid secretion rate in (A) a control and (B) a duodenal ulcer patient. In a control subject (A) the secretion rate is at a low level throughout the night, even during REM periods. In the ulcer patient (B) the secretion rate is markedly increased in relation to REM periods; between REM periods it decreases markedly.
Repetitive leg twitches causing arousals from sleep are referred to as Periodic Leg Movements, they are a common cause of insomnia in the elderly (Figure 3). Shift work and jet lag produce a mismatch between one's normal sleep time and one's endogenous circadian rhythm; depending on the mismatch, people have difficulty initiating or maintaining sleep.
Sleepiness is a physiological drive usually resulting from sleep deprivation
(see Part K., Daytime Sleepiness and Alertness). It can be determined by using
the Multiple Sleep Latency Test which measures the length of time required to
fall asleep. When sleepiness is chronic and severe, the individual may become
less aware of sleepiness and so may fall asleep without warning: these episodes
are called sleep attacks.
Sleepiness is a normal experience after prolonged wakefulness, as in the case
of an intern who has been awake close up night. Mild sleepiness is most apparent
during passive or boring situations, such as reading or watching Geraldo Rivera.
With more severe sleepiness, the patient may have difficulty staying awake during
more active conditions, such as during conversations or meals. Sleepiness is
excessive and an indication of a sleep disorder when it occurs at inappropriate
or undesirable times, such as at work, when driving, or during reproductive
behavior. Sleepiness that is not relieved by increased amounts of sleep at night
is usually a sign of a sleep disorder.
Chronic or excessive sleepiness is accompanied by lapses of attention and by
impaired motor and cognitive abilities; these are particularly evident during
boring tasks. Chronic sleepiness is diagnosed primarily by an evaluation of the
patient's history and by sleep latency testing, because it is seldom apparent by
physical examination. Dropping eyelids, loss of postural muscle tone and small
pupils, however, may be present when sleepiness is severe.
Sleepiness due to sleep deprivation or to a sleep disorders must to be
distinguished from sleepiness that is associated with clouded consciousness or
sedation. Although patients with clouded consciousness due to bihemispheric or
brainstem lesions are drowsy, they are usually confused and suffer greater
degrees of inattention and cognitive impairment than is customary with chronic
sleepiness.
Periodic leg movements in a patient with the
"restless leg syndrome." The movements recur approximately every 30
sec.
Excessive Daytime Sleepiness
| Narcolepsy | Upper Airway Sleep Apnea | |
|---|---|---|
| Sex | male & female | male |
| Age | 2 & 3 decades | 5 & 6 decades |
| EDS | yes | yes |
| Naps | short & refreshing | long & not refreshing |
| Alert upon Awakening | yes | no |
| Cataplexy | yes | no |
| Heavy Snoring | no | yes |
| Diastolic Hypertension | no | yes |
| Morbid Obesity | no | often |
| Course | non-progressive | progressive |
Unlike insomnia, which has a multitude of etiologies, patients with complaints
of sleepiness typically have one of two disorders: narcolepsy or obstructive
sleep apnea (see above). Patients with narcolepsy not only complain of
sleepiness but also of auxiliary symptoms. The auxiliary symptoms of narcolepsy
are cataplexy, hypnagogic hallucinations, and sleep paralysis (Figure 4).
Cataplexy refers to a sudden weakness due to decreased muscle tone that is
typically triggered by an emotional event. Hypnagogic hallucinations are visual
hallucinations (dreams) experienced at sleep onset. Finally, sleep paralysis is
characterized by a partial or total paralysis of skeletal muscles at sleep onset.
Today it is well recognized that these auxiliary symptoms are manifestations of
REM sleep intruding into wakefulness. In fact, patient with narcolepsy will
frequently demonstrate sleep onset REM periods.
Obstructive sleep apnea is a disorder in which the patient's airway is obstructed during sleep. The obstruction is terminated by an arousal from sleep. This cycle of apnea and arousal from the apnea repeats itself hundreds of times during the night. It is this fragmentation of sleep which leads to the complaint of daytime sleepiness. Aside from sleepiness, there are cardiovascular risks of apnea. Patients with apnea have higher rates of systemic hypertension and stroke. Recently, it has been shown that sleep apnea is associated with greater mortality.
Sleepwalking is more common in children than in adults. It is most likely to occur during the first third of the night, particularly during the first NREM period. The child typically sits up in bed or stands and walks aimlessly with purposeless and clumsy movements. The eyes are open but "glassy" and "unseeing." The child may dress or undress, fumble with objects, mumble or moan, and walk to different rooms or even outside the house. The child usually does not respond to another's voice but often can be led back to bed. Although usually avoiding objects, the child may be injured by falling or by touching hot objects. There is usually no recall or only fragmentary, dreamlike recollections of the events. The episodes last 15 secs to 30 mins. An arousal pattern of synchronous delta activity similar to hypnagogic hypersynchrony may occur prior to the sleepwalking episode.
The polygraphic record of a sleepwalking incident. A high voltage, slow wave electroencephalographic pattern begins as the subject sits up, and sleep is maintained throughout the episode.
In most cases, the timing of sleepwalking and the associated behavior make diagnosis straightforward. Rarely, sleepwalking is a manifestation in an epileptic patient of a nocturnal complex partial seizures the diagnosis may then require a polysomnographic test. In the elderly demented patient, nocturnal wandering is more often due to waking disorientation than to sleepwalking.
Sleep terrors, also called pavor nocturnus, are events which usually occur during Stages 3 and 4 of NREM sleep. Like sleepwalking, sleep terrors are most common in children. They are characterized by arousal, agitation, and signs of sympathetic overactivity, including large pupils, sweating, tachycardia, tachypnea, and increased blood pressure. The child appears terrified, screams, and is usually inconsolable for several minutes, after which he or she relaxes and returns to sleep. Usually there is either amnesia for the event or only a vague memory or terror, impending death, or burial. Sleep terrors may overlap with sleepwalking, in which case walking or running occur in conjunction with shouting, jumping and flailing about. Milder episodes, or confusional arousals, may be accompanied only by moaning, muttering, and/or thrashing.
Sleep terrors can be distinguished from nightmares by the occurrence of amnesia for the event; however, the distinction from nocturnal complex partial seizuresu may be more difficult. Sleep terrors usually occur early in the night and may be precipitated by emotional stress; whereas seizures may occur at any time during the night. In some cases, differentiation from seizures requires a sleep laboratory evaluation. In older patients with episodes of violent behavior or screaming resembling sleep terrors, polysomnography may reveal evidence of REM Sleep Behavior Disorder.
REM Sleep Behavior Disorder occurs during pathological REM sleep. It is a complex, vigorous or violent behavior which is sometimes associated with dreamlike thoughts and images. Patients with REM Sleep Behavior Disorder may complain of sleep disruption, violent behavior with injuries to himself or herself or to their bed partner, or unpleasant, vivid dreams. Although in most people muscle atonia limits movements during REM sleep to brief twitches, in patients with REM Sleep Behavior Disorder there is an abnormal preservation of muscle tone during some or all of REM sleep. The patients are usually middle-aged or elderly and frequently have a neurological disease.
REM Sleep Behavior Disorder may be mistaken for night terrors, nightmares, panic attacks or seizures. The accompanying dream imagery and mentation, the occurrence in older persons, and the lack of pronounced autonomic activation are features that help to differentiate REM Sleep Behavior Disorder from night terrors. Prominent motor activity is not a feature of nightmares, and nocturnal anxiety and panic attacks are usually not associated with violent behavior or injuries. Although partial complex seizures are rarely associated with dream enactment, polysomnographic studies may be required to exclude seizures as the etiology.
