Chapter 57 Cardinal Manifestations of Sleep Disorders
Sleep disorders include a wide range of disorders that impair health and quality of life. Clinicians must efficiently identify individuals with sleep disorders and direct effective treatment of these disorders. The fundamental symptoms of sleep disorders include insomnia, hypersomnia, and unusual sleep-related behaviors, but more subtle signs and symptoms may also provide clues to an underlying sleep dysfunction. Insomnia, a symptom of difficulty initiating or maintaining sleep with daytime sequelae, can be related to many contributing factors. Features that predispose to, precipitate, and perpetuate the insomnia can be identified in individuals who suffer from primary and secondary insomnias. Insomnia can have an intricate relationship to other medical and psychiatric disorders. Hypersomnia, often associated with excessive daytime sleepiness, consists of sleep propensity during the wake period. Sleepiness can be subjectively and objectively quantified to give clues differentiating this symptom from fatigue. Other symptoms, such as snoring, apnea, and morning headache, may indicate potential sleep-related breathing disorders or other medical problems. Cataplexy, as a symptom of sudden loss of muscle tone in relation to an emotional trigger, rarely occurs in isolation. In combination with excessive sleepiness, cataplexy should prompt an evaluation for narcolepsy. Restless legs syndrome, associated with discomfort and the urge to move extremities during periods of inactivity, is worse in the evenings and relieved with movement. Periodic limb movements in sleep can occur in association with restless legs syndrome and may involve movements of the upper or lower extremities. Other parasomnias, such as sleepwalking, sleep terrors, and dream enactment, require detailed description of the sleep-related behaviors to help differentiate potential causes. In this chapter, we review the major symptoms, discuss the physical findings, and highlight some of the key features of sleep disorders.
Sleep is essential to health, restoring properties that promote wakefulness and a sense of well-being. Sleep disturbance, however, frequently disrupts this sense of well-being and can result in a wide range of systemic and psychological symptoms. Sleep disruption frequently is manifested as intrusion of components of the sleep state into periods of wakefulness or vice versa. Beyond the medical manifestations, sleep disruption may impair work performance and psychosocial interactions. As we realize the connection of sleep to good health, we also recognize that sleep disruption may exacerbate symptoms of other diseases. These manifestations may present as worsening of a preexisting disorder or impairment of the patient’s ability to cope with its symptoms. The challenge for physicians is to recognize these manifestations and appropriately delineate them as related to dysfunction of sleep.
Most patients referred to sleep centers present with one or a combination of three classic complaints: excessive sleepiness, difficulty attaining or sustaining sleep, or unusual events associated with sleep. These symptoms can be easily recognized as related to sleep and are not mutually exclusive. Patients may note more than one problem, such as difficulty sleeping at night and excessive sleepiness during the day. Others may complain of unusual events at night with daytime sleepiness or inability to sleep. Each of these symptoms conveys clues to the underlying pathologic process (Figs. 57-1 to 57-3). In this chapter, we review the cardinal manifestations of sleep disorders and address some of the key features that guide the clinician to pursue further diagnostic evaluations.
Figure 57-3 Diagnostic flow chart to approach unusual nocturnal events. CHF, congestive heart failure; GERD, gastroesophageal reflux disease; NREM, non–rapid eye movement; REM, rapid eye movement; RLS, restless legs syndrome.
Insomnia is the complaint of difficulty initiating or maintaining sleep or of unrefreshing sleep combined with daytime sequelae. This combination of poor nighttime sleep with an adverse effect on daytime activities is important to establishment of the complaint as insomnia. The daytime manifestations of insomnia may take the form of excessive fatigue, impairment of performance, or emotional change. Individual sleep need may vary significantly. Some people may feel fine and note no impairment of performance with 5 hours of sleep per night, whereas others may need more than 9 hours to preserve daytime functioning. Thus, the requirement of daytime sequelae differentiates individual sleep need from the complaint of insomnia.
Most people have an occasional night fraught with difficulty falling asleep or trouble maintaining sleep. These occasional nights might be closely linked to the surrounding events of the day, psychological challenges, or sudden changes in environment or medical condition. Surveys have shown that approximately 35% of individuals complain that their sleep is disrupted and that a smaller group, of approximately 10%, have a more persistent insomnia.1 For these patients, lack of “good-quality” sleep produces a greater disruption of life and may lead to more significant medical symptoms.
As a symptom, insomnia is directly related to the patient’s perception of poor sleep. Patients with insomnia believe that the sleep disruption produces their excessive sleepiness, fatigue, lack of concentration, muscle aches, and depression. Patients with insomnia frequently will describe themselves as tense, anxious, nervous, tired, irritable, unable to relax, obsessively worried, and depressed. Many of these traits may predate the onset of the insomnia, but others may occur after the onset of the poor sleep. These individuals also believe that a good night’s sleep would reverse their symptoms.
Patients with insomnia frequently give historical clues directed toward the mechanisms behind their insomnia. The symptom complex may indicate an underlying disorder related to primary failure of the sleep mechanics or one in which sleep disruption is the byproduct of another disorder. As sleep is an active process, neuronal networks involved with sleep induction must be engaged and networks involved in wakefulness must be diminished for sleep. Rarely do patients have just one factor responsible for their chronic insomnia. Most patients have factors that put them at risk for development of insomnia, for initiation of the insomnia, and for perpetuation of the insomnia. The presence of predisposing, precipitating, and perpetuating factors emphasizes the nature of insomnia as an ongoing process, and clinicians need to search for these contributing factors to outline an effective treatment course (see Chapters 75, Chapter 77, and Chapter 78).
Epidemiologically, insomnia appears to be more common in women, older individuals, and those with psychiatric or chronic medical illness. Insomnia is also more common in those with lower socioeconomic status and poor education. Behavioral traits such as obsessive-compulsive nature, frequent rumination, and poor coping strategies and “hyperalert” individuals are correlated with greater risk for insomnia. “Hyperarousal” documented on recent neuroimaging studies may explain the neurophysiologic basis of these associated factors predisposing to chronic insomnia.
Insomnia may be initiated by sudden changes in environment or challenges to the body or mind. These challenges may come in the form of acute medical illness, psychological or psychiatric events, shift in schedule, or changes in medications or supplements. Initiating events may play little role in the patient’s current ongoing process but give important clues to preventing further recurrence of the insomnia.
Many patients, attempting to improve their sleep, will adopt behaviors that actually perpetuate the insomnia. Patients may employ rituals and endorse “remedies” that convert the short-term insomnia into a chronic form. During this evolution, the patient may take on changes in sleep schedule, depend on certain somnogenic substances, or develop secondary medical or psychological issues. Many of these behaviors conflict with typical sleep hygiene practices, producing an environment detrimental to sleep. Such maladaptive habits may occur during the day or night and include issues such as heavy caffeine or alcohol use, watching television or playing video games while in bed, and even eating or exercising during the usual sleep period. Some patients will describe that television or radio distracts them from intrusive thoughts. Others may develop sleep associations to counterbalance negative events. A subgroup of patients actually fear going to bed or have performance anxiety over the oncoming sleep period. This expectation of poor sleep promotes the apprehension toward sleep and may perpetuate counterproductive sleep rituals. These maladaptive behaviors become the predominant feature of psychophysiologic insomnia.
Timing of the insomnia during the sleep period may also be helpful. Circadian rhythm disorders can masquerade as complaints of insomnia or excessive sleepiness, and patients with insomnia may develop dysfunction of their circadian rhythm. Difficulty with the onset of sleep suggests an underlying delayed sleep phase or occasionally depression in younger adults. Insomnia with early morning arousal raises the possibility of underlying depression or advanced sleep phase. Schedule changes, such as from jet lag or shift work, are important clues, and sleep diaries of bedtime and wake time can be useful in determining potential links to schedule or circadian rhythm issues.
Perception of good sleep is an important factor in evaluating the complaint of insomnia. Some patients exaggerate their symptoms, whereas other patients may not perceive that they are asleep. Paradoxical insomnia is one form of the primary insomnias. Individuals who have this disorder display the normal physiologic parameters of sleep but do not recognize that they have slept. Other patients may endorse unrealistic expectations or unobtainable goals. Patients may assume that sleep should not be interrupted by any arousals or that one must sleep a set number of hours. These beliefs can be easily addressed with education of the patient. Another primary insomnia, idiopathic insomnia, is not associated with clear inciting factors. These individuals usually have lifelong difficulty of sleep and may have significant family history. These primary insomnias are discussed further in Chapters 75 and 77.
Medical or neurologic disorders may precipitate and perpetuate insomnia. Derangement of almost any system in the body can disrupt sleep. Patients with heart, liver, or renal failure or disturbances of the gastrointestinal system or pulmonary disease commonly complain of insomnia. Patients with fulminant rash or significant burns frequently note disturbed sleep, and urologic issues such as nocturia may provoke frequent arousals. Neurologic disorders also promote sleep disruption. Patients with neuromuscular disorders may have discomfort or inadequate ventilation at night that provokes insomnia. Some patients with stroke will note insomnia or sleep disruption after their vascular event. Paralysis from central or peripheral nervous system disorders can result in nighttime discomfort from inability to move. Patients with Parkinson’s disease may have akinesis, tremor, or medication effect, and patients with dementia may have circadian abnormalities that promote awakenings at night.
Pain can disturb sleep and promotes insomnia. Musculoskeletal discomfort may become worse with periods of rest. Pain from entrapment neuropathies, such as carpal tunnel syndrome, is typically worse at night; headaches, such as cluster headache, and even pain related to increased intracranial pressure or brain mass lesions can become more intense during sleep. Restless legs produce significant discomfort and are classically worse in the evening, before the onset of sleep. Arthritis and other rheumatologic disorders frequently can disrupt sleep by increasing nighttime pain and stiffness.
Nearly all of the psychiatric illnesses have some link to poor sleep. Patients with depression or anxiety disorders may have insomnia years before the presentation of the affective component. Although the cause and effect are still in debate, the association is clear. Insomnia may herald the onset of psychosis or mania.
The clinician may uncover few physical findings in patients with insomnia. Anxious or hyperalert individuals may demonstrate mild tachycardia, rapid respiratory rate, or cold hands. These individuals may startle easily or be easily distracted during the interview. The clinician should look carefully for signs of obstructive sleep apnea, narrow airway, and obesity because these too can be manifested as insomnia. Signs of Cushing’s syndrome (round face and buffalo hump) or hyperthyroidism (tachycardia and excessive sweating) are important clues to an endocrine disorder. Each patient with insomnia should have a complete neurologic examination to look for potential neurologic lesions impairing sleep. This examination should include an assessment of cognition, mood, and affect. The Mini Mental State Examination is one tool that helps assess cognitive abilities and can be followed over time.2 Clinicians can also use the Minnesota Multiphasic Personality Inventory to identify personality and affect issues.
Sleepiness is a common symptom noted by 5% to 20% of individuals.3,4 Most individuals can relate some instances of falling asleep when they intended to be awake. Sleepiness is a normal feeling as one approaches a typical sleep period or after prolonged wakefulness. Excessive sleepiness occurs when one enters sleep at an inappropriate setting or has episodes of unintentional sleep. Excessive sleepiness can occur in degrees. In mild sleepiness, one might fall asleep while reading a book or while sitting quietly. This degree of sleepiness may produce only limited impairment in the person’s perceived quality of life. Greater degrees of sleepiness may be associated with bouts of irresistible sleep or sleep attacks. Irresistible sleep may intrude on such activities as driving, having a conversation, or eating meals. This degree of sleepiness may place the patient at significant risk for accidents and have a major impact on the person’s health and sense of well-being.
As with other subjective symptoms, an individual’s perception of sleepiness influences the complaint. Some patients may overreport the degree of sleepiness and note sleepiness even during periods of normal wakefulness. Other individuals may underreport and not recognize periods of sleepiness. For some of these individuals, sleepiness may be described as periods of lapse of attention or diminished cognitive abilities, such as missing an exit on the highway or brief delay in performing a task. Perception of sleepiness is also reduced with continued sleep deprivation. Individuals who are chronically sleep deprived become accustomed to their impairment and are less likely to recognize their degree of sleepiness.
Clinicians should always question their hypersomnic patients for clues of potential sleep debt, dyssomnia, or medical or psychiatric causes. Sleep deprivation is common in our society, and patients should be queried about their schedule during the week and weekends. Information about sleep habits and environment may disclose important factors contributing to the sleepiness.
Excessive sleepiness may result from a wide range of medical disorders and medication. Patients with heart, kidney, or liver failure and rheumatologic or endocrinologic disorders such as hypothyroidism and diabetes may note sleepiness and fatigue. Neurologic disorders, such as strokes, tumors, demyelinating diseases, and head trauma, can evoke excessive sleepiness. Sleepiness is frequently the cardinal symptom of many sleep disorders. Patients with sleep apnea and narcolepsy, restless legs syndrome–periodic limb movements, and even parasomnias may note excessive daytime sleepiness as their main complaint. Historical features of snoring, observed apneas, morning headaches, cataplexy, sleep paralysis, hypnagogic hallucinations, and confusion on arousals suggest contributions of a specific sleep disorder. Individuals with idiopathic hypersomnolence have unrelenting daytime sleepiness despite prolonged periods of sleep, which differentiates this disorder from sleep deprivation.
Physical findings are few in patients with sleepiness. Frequent pauses, slowed responses, drooping eyelids, and repetitive yawning support the complaint of sleepiness. Patients may be asleep when the clinician enters the examination room, and some patients may show signs of chronic sleepiness, such as dark circles under the eyes. The patient’s neurologic examination may show findings of inattentiveness or even brief “microsleeps.”
Sleepiness can be quantified subjectively by questionnaires or by physiologic measures such as a multiple sleep latency test. The Epworth Sleepiness Scale is one example of a quantifiable subjective measure of sleepiness and has been translated into several languages (Table 57-1).5 In this scale, the individual is asked to rate on a scale of 0 to 3 (0, no chance; 3, high likelihood) the chance of dozing in a series of eight situations. This score has a modest correlation with physiologic measures of sleep but has a better correlation with the respiratory disturbance index in patients with obstructive sleep apnea (Table 57-2).
|Today’s date: ______________________________________________ Your age (years): ______________________________________________|
|Your sex (male = M; female = F): _____________________________________________________________________________________________|
|How likely are you to doze off or fall asleep in the following situations, in contrast to feeling just tired? This refers to your usual way of life in recent times. Even if you have not done some of these things recently, try to work out how they would have affected you. Use the following scale to choose the most appropriate number for each situation:|
|SITUATION*||CHANCE OF DOZING|
|Sitting and reading||________|
|Sitting, inactive in a public place (e.g., a theater or a meeting)||________|
|As a passenger in a car for an hour without a break||________|
|Lying down to rest in the afternoon when circumstances permit||________|
|Sitting and talking to someone||________|
|Sitting quietly after a lunch without alcohol||________|
|In a car, while stopped for a few minutes in traffic||________|
|Thank you for your cooperation.|
From Johns MW. A new method for measuring daytime sleepiness: the Epworth Sleepiness Scale. Sleep 1991;14:540-545.