Sleep Disorder - Diagnosis

Diagnosis of sleep disorders

The approach to the diagnosis and treatment of sleep disorders presented in this chapter is aimed at physicians who see patients in outpatient clinics. The current situation is such that a general practitioner with a long queue outside his door can only spend a very limited time seeing a patient. Nevertheless, it is recommended that the patient be asked several questions regarding the quality of sleep, the presence of daytime sleepiness, and the state of his performance. If the patient reports any disturbances in answer to these questions, he should be subjected to a comprehensive and in-depth examination.

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Initial examination

It has already been noted that not all patients suffering from sleep disorders mention it during a visit to the doctor. Even more rarely, patients specifically contact the doctor about this. Nevertheless, sleep disorders are quite common and have an adverse effect on well-being, performance, quality of life, general health and emotional well-being. Given these circumstances, a brief but comprehensive (“screening”) assessment of the state of sleep and wakefulness should become an indispensable part of the patient’s routine outpatient examination.

The initial assessment of sleep quality should include several aspects related to common sleep disorders. The most common sleep disorder is insomnia, but this is not a nosological or even a syndromic diagnosis, but rather a statement that the quality of sleep is unsatisfactory. Insomnia may manifest itself as one or more of the following symptoms:

1. sleep disturbances;
2. frequent awakenings during the night (sleep maintenance disorders);
3. premature morning awakening;
4. lack of feeling of rest or refreshment after waking up (dissatisfaction with the quality of sleep).

When assessing sleep status, it is recommended to begin with open-ended questions about the patient's overall satisfaction with sleep, followed by a few follow-up questions regarding specific symptoms.

The second most important manifestation of sleep disorders is increased daytime sleepiness. It can be the leading symptom of a number of primary sleep disorders, including obstructive apnea, PDKS, and narcolepsy. In severe cases, during a doctor's examination, patients are so sleepy that they can hardly maintain a conversation. More often, however, milder cases of daytime sleepiness are observed, when patients report only increased fatigue and loss of strength. As in the case of insomnia, in order to identify daytime sleepiness, the patient needs to be asked several clarifying questions.

Sleep disturbances may also manifest themselves as somatic or behavioral changes. For example, pronounced snoring, irregular breathing, a feeling of suffocation during sleep are characteristic of obstructive sleep apnea, frequent repetitive twitching or kicking of the legs is a sign of PDKS. Collecting information about the patient's behavior during sleep helps to identify parasomnias, such as somnambulism or night terrors.

A separate category of sleep disorders is sleep-wake cycle disorders. In some patients, due to endogenous factors, there is a temporary shift in the sleep-wake cycle in relation to the usual rhythm. For example, people with premature sleep phase syndrome fall asleep early in the evening, but also wake up early in the morning. At the same time, with delayed sleep phase syndrome, a person falls asleep only late at night and wakes up during the day. In both cases, the structure and quality of sleep itself are not affected. Other types of sleep-wake cycle disorders (i.e., circadian rhythm) are associated with professional or behavioral factors. Common examples of such disorders are sleep disorders associated with changing time zones (for example, during long flights) or shift work.

Thus, during the initial examination, the physician should ask several specific questions regarding the quality of sleep and manifestations of sleep disturbances. It is also important to inquire whether the person feels alert or sleepy during the day. Then, it is necessary to find out whether any somatic or behavioral changes are noted during sleep (for example, snoring, pronounced leg movements, or agitation). Finally, one or two questions should be asked about the person’s usual sleep and wake times, in order to exclude disorders associated with circadian rhythm disturbances. Thus, this initial interview involves a limited number of direct questions and can be completed fairly quickly. If any symptoms are detected, a comprehensive examination is necessary to diagnose a possible sleep disorder.

In-depth examination

When one or more symptoms are detected that indicate a sleep disorder, a more in-depth, comprehensive examination is necessary in order to establish a diagnosis, identify the etiologic factors if possible, and plan treatment accordingly. This approach is similar to the usual actions of a physician who deals with a particular somatic symptom (for example, fever or chest pain), which can be caused by a variety of diseases and each of which requires specific treatment. In the case of disorders, it is important to remember that insomnia is a symptom, not a diagnosis. In clinical practice, an incorrect stereotype has developed: the detection of insomnia entails the prescription of a sleeping pill - instead of stimulating a thorough search for its cause. Below, the recommended approach to sleep disorders is described in more detail, using insomnia as an example.

When analyzing the patient's complaints about sleep disorders, it is necessary to obtain additional anamnestic information in order to arrange them into a certain system. It is necessary to detail the nature of the main complaints, ask about other groups of symptoms that are possible with sleep disorders, about the patient's lifestyle and external factors that can contribute to sleep disorders. Important additional information can be provided by the patient's spouse or partner - only from him/her can you find out whether the patient snores, whether he/she makes leg movements in his/her sleep, whether he/she breathes evenly.

Insomnia may occur against the background or as a result of a number of diseases, which forces us to ask an additional series of questions. Information about the persistence of sleep disorders is of great importance, which is necessary for establishing a diagnosis and choosing adequate therapy. Insomnia is usually classified as follows:

1. transient, lasting for several days;
2. short-term - up to 3 weeks and
3. chronic - persisting for more than 3 weeks.

Many factors can trigger sleep disturbances. It is well known that stress is one of the most important external factors that adversely affects sleep quality. According to a 1995 Gallup poll, 46% of respondents said that their sleep disturbances were related to stress or anxiety. About a quarter of respondents with sleep disorders believe that it is impossible to achieve career success without sacrificing sleep. In this regard, it is necessary to identify newly emerging or long-standing stress factors that can negatively affect sleep. Discussing these factors with the patient and analyzing their importance will help him or her understand the causes of sleep disturbances and make efforts to change the circumstances of his or her life. In some cases, the patient should be referred to a psychologist or psychotherapist to help him or her cope with stress more effectively.

Sleep is often significantly affected by the home environment, daily routine, and habits. The term "sleep hygiene" is used to describe a wide range of these aspects. When discussing sleep hygiene issues, it is useful to find out the patient's habits, how he or she usually goes to bed or gets up. A frequent cause of sleep disorders is failure to adhere to a certain daily routine. The bedroom environment is also important. Sleep can be disrupted because the room is too noisy, too cold or hot, or too light. Sleep quality can be affected by a late heavy dinner, eating spicy food at night, or exercising before bed. In this regard, it is useful to ask the patient to keep a diary for several weeks, recording the time and quality of nighttime sleep, daytime naps, level of wakefulness during the day, and habits or actions related to sleep. Analysis of diary entries often reveals factors contributing to sleep disorders.

A number of substances and medications can disrupt sleep. Although caffeine is known to have an adverse effect on sleep, many people do not monitor the amount of coffee they drink or drink it too late. In addition, it is often not taken into account that tea, cola, and chocolate contain a significant amount of caffeine. Sleep disorders are often associated with alcohol consumption. Although alcohol has a sedative effect and can reduce the latency period of falling asleep, it causes sleep to become fragmented and restless. Many patients with insomnia, especially those associated with anxiety or depression, begin to use alcohol on their own as a sleeping pill. However, this method is ineffective in the long term due to the ability of alcohol to cause sleep fragmentation. In addition, if a person is used to falling asleep with alcohol, attempts to stop drinking it will provoke rebound insomnia, which in the long term can lead to alcohol addiction.

A number of drugs prescribed for somatic, neurological or mental disorders have a significant impact on sleep. Some drugs (for example, the antidepressant amitriptyline, various antihistamines) cause a pronounced sedative effect and can be the cause of daytime sleepiness.

Sleep disorders in somatic and neurological diseases

Sleep disorders can be caused by a number of somatic and neurological diseases. Therefore, when examining a patient with complaints of sleep disorders, attention should be paid to possible signs of thyroid dysfunction (hypothyroidism or thyrotoxicosis), lung diseases (bronchial asthma, chronic obstructive diseases), gastrointestinal disorders (for example, esophageal reflux), neurological diseases (for example, Parkinson's disease), which can disrupt sleep. Any condition accompanied by severe pain syndrome can lead to sleep disorders. An example is fibromyalgia. With this disease, characterized by muscle pain and the presence of multiple specific painful points, insomnia is often observed, and polysomnography during slow sleep reveals alpha rhythm inclusions (the so-called "alpha-delta sleep").

Medical conditions that cause sleep disturbances may be revealed by physical examination and laboratory testing. Whenever possible, one should always try to find and treat the underlying cause of the sleep disturbance, rather than the insomnia itself.

Mental disorders and sleep disorders

Many mental illnesses are associated with sleep disorders, especially insomnia. Therefore, examination of a patient with sleep disorders must necessarily include an assessment of mental status. Sleep disorders are common in patients with schizophrenia and Alzheimer's disease, but it is especially important to identify anxiety and affective disorders, since these patients first consult general practitioners and often with complaints of sleep disorders. Approximately 70% of patients with depression complain of insomnia, with complaints of intermittent restless sleep or premature morning awakenings being particularly typical. In one study, 90% of hospitalized patients with depression were found to have sleep disorders confirmed by EEG. Numerous polysomnographic studies have revealed characteristic changes in sleep architecture in patients with depression: sleep fragmentation, changes in REM sleep (e.g., shortening of the latent period of REM sleep), and reduction of slow sleep.

At the same time, a significant proportion of patients with depression (approximately 20%) suffer not from typical insomnia, but, on the contrary, from daytime sleepiness, which can manifest itself as periodic hibernation or rapid fatigue. Such cases are sometimes called atypical depression. Hypersomnia is also often observed in patients in the depressive phase of bipolar disorder, as well as in seasonal affective disorder.

The relationship between depression and sleep disorders is complex. It can be difficult to decide whether a sleep disorder is a symptom of depression or a factor that triggers a depressive episode. Some depressed patients claim that their “depression goes away” if they manage to sleep well for a few nights. However, there are currently virtually no systematic studies that would determine the extent to which treating insomnia directly can affect the symptoms of depression. However, it should be noted that in many cases, doctors do not recognize depression and do not prescribe adequate therapy because they focus exclusively on the symptoms of insomnia and other somatic complaints. It is generally recognized that prescribing only sleeping pills to patients with depression cannot be considered adequate therapy. This situation is especially dangerous due to the serious risk of suicide.

Factors Contributing to Chronic Insomnia

When examining a patient with insomnia, one should try to identify not only the factors that provoked insomnia, but also the factors that contribute to its chronicity. In particular, many patients with acute severe insomnia have pronounced anxious doubts about whether they will be able to fall asleep or not. Often, patients are overcome with anxiety as soon as they cross the threshold of the bedroom. Constant concern about the prospect of another sleepless night is reinforced by concern about a possible decrease in work capacity or serious health problems that may arise due to sleep disturbance. The situation is often complicated by inadequate actions of the patients themselves, with the help of which they try to normalize sleep (for example, they can doze during the day and drink alcohol at night). This type of sleep disorder is called psychophysiological insomnia. If psychophysiological insomnia is diagnosed, then in addition to eliminating the primary factors that provoked the sleep disorder, it is necessary to correct the secondary psychological problems that support it.

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Examination of a patient with increased daytime sleepiness

Increased daytime sleepiness is a condition that is closely related to sleep disorders and is often encountered in general practice. Like insomnia, daytime sleepiness is a reason for a comprehensive in-depth examination of the patient. When symptoms of increased daytime sleepiness are detected, its cause must be sought in a fairly wide range of diseases.

First of all, a thorough assessment of the symptoms and their severity is necessary. It is necessary to find out the circumstances of the symptoms, the factors that contribute to their intensification or weakening, the state of night sleep. A survey of systems and organs, a physical examination, a comprehensive laboratory study will allow you to exclude a somatic or neurological disease that may be the cause of increased daytime sleepiness. It is very important to clarify what medications the patient is taking, since they also often cause drowsiness.

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Conditions that cause excessive daytime sleepiness

• Lack of sleep (due to various reasons)
• Some somatic diseases (eg, hypothyroidism)
• Side effects of medications (antihistamines, antidepressants, adrenergic blockers)
• Depressive disorders (especially bipolar disorder and atypical depression)
• Idiopathic hypersomnia
• Periodic limb movements during sleep
• Obstructive sleep apnea
• Narcolepsy

Primary sleep disorders that commonly cause daytime sleepiness include narcolepsy and obstructive sleep apnea. Therefore, the patient should be asked a number of questions about these conditions. Narcolepsy, in addition to increased daytime sleepiness, is characterized by cataplexy (transient muscle weakness, usually provoked by an intense emotional reaction), sleep paralysis (a transient state of immobility after awakening, which is probably associated with a short-term prolongation of muscle atonia characteristic of REM sleep), hypnagogic hallucinations at the moment of falling asleep and awakening. Obstructive sleep apnea is often noted in individuals who are overweight, have a short, massive neck, or other features that contribute to upper airway obstruction. Typically, these patients are characterized by pronounced snoring, fragmented, restless, unrefreshing sleep, headache and confusion in the morning, and a feeling of suffocation at night. PSG is necessary to confirm the diagnosis of narcolepsy and obstructive sleep apnea.

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Use of polysomnography in the diagnosis of sleep disorders

To confirm the diagnosis of primary sleep disorders (including obstructive sleep apnea, narcolepsy, PDCS, REM sleep behavior disorder), and sometimes to determine the cause of insomnia, a laboratory study of night sleep is required. Due to the technical complexity and high cost, polysomnographic research should be carried out strictly according to indications. In this regard, doctors should have a clear idea in which cases a patient should be referred to a somnology laboratory.

Obstructive sleep apnea is the most common indication for PSG. Because this condition causes frequent complications and is associated with increased mortality, its accurate diagnosis is of utmost importance. Although obstructive sleep apnea may be suspected based on clinical findings, the diagnosis can only be confirmed by PSG. The diagnostic technique for obstructive sleep apnea typically requires testing over two nights. During the first night, apnea is confirmed, and during the second night, the effectiveness of the method based on the creation of continuous positive airway pressure (CPAP) in the upper airways is assessed. In the abbreviated version of the study, conducted over one night, the presence of apnea is confirmed during the first half of the night, and the most effective CPAP parameters are selected during the second half. PSG counts the number of apnea or hypopnea episodes during the night. Each such episode is usually accompanied by awakening, which leads to sleep fragmentation. In addition, a decrease in the oxyhemoglobin level is usually detected. There is some controversy regarding the threshold frequency of apnea and hypopnea episodes that allows diagnosing this disease. According to the most common opinion, the diagnosis can be made if the number of apnea and hypopnea episodes is at least 15 per hour. In many patients, the frequency of these episodes is significantly higher and sometimes exceeds 100 per hour. Fragmentation of night sleep is the direct cause of the fact that patients usually experience pronounced daytime sleepiness. The cessation of air flow is usually accompanied by intense respiratory movement, which can be judged by the activity of the muscles of the chest, diaphragm, and abdomen. In the absence of such activity, central sleep apnea is diagnosed.

Narcolepsy is another primary sleep disorder, the diagnosis of which requires PSG. The main clinical manifestations of narcolepsy - increased daytime sleepiness, cataplexy, sleep paralysis and hypnagogic hallucinations - allow us to suspect this disease. Laboratory testing required to confirm the diagnosis includes not only recording of nighttime sleep but also conducting a daytime study - the multiple latent periods of sleep (MLPS) test. The MLPS test is especially widely used for objective quantitative assessment of daytime sleepiness. A study of nighttime sleep in narcolepsy allows us to identify changes in the quality and architecture of sleep. Many patients have fragmentation of nighttime sleep and premature onset of REM sleep. The MLPS test is conducted the day after the nighttime sleep study. The patient is asked to lie down and try to fall asleep every 2 hours (for example, at 9, 11, 13 and 15 hours). 20 minutes after each attempt to fall asleep, the patient is awakened and made to stay awake until the next attempt to fall asleep. The average time to fall asleep (over 4 attempts) and the type of sleep that occurs are assessed. If the average latent period of sleep is less than 5 minutes, pathological sleepiness can be diagnosed. Although a decrease in the latent period of sleep is typical for patients with narcolepsy, it is not pathognomonic and can be observed in other conditions - obstructive sleep apnea, idiopathic hypersomnia, sleep disorder or deprivation. More specific for narcolepsy is a shortened latent period of REM sleep - this can also be detected using the MLPS test. According to the established criteria, a diagnosis of narcolepsy can be established if REM sleep is recorded in at least 2 of 4 attempts to fall asleep.

PSG is also important in the diagnosis of other sleep disorders. Periodic limb movements during sleep are characterized by stereotypical movements that repeat every 20-40 seconds. These movements also lead to sleep fragmentation, which is expressed in complaints of restless, unrefreshing sleep and daytime sleepiness.

REM sleep behavior disorder is characterized by behaviors, sometimes violent or aggressive, that appear to reflect the patient's response to and content of dreams. PSG has shown that these behaviors occur during REM sleep and are associated with the absence of the muscle atonia typically seen during this stage. If the patient's history suggests REM sleep behavior disorder, the absence of muscle atonia during REM sleep is sufficient to confirm the diagnosis, even if no REM behaviors were observed during the night's sleep recording. Because REM sleep behavior disorder may be associated with lesions in the midbrain or other brainstem regions, further investigations, including brain imaging, are needed if PSG confirms the presence of this brain disorder.

Epileptic seizures are often associated with sleep and sometimes occur exclusively during sleep. Nocturnal epileptic seizures can often be diagnosed using PSG alone; however, additional leads are needed to detect epileptic activity on the EEG.

In insomnia, PSG is not usually performed because the nonspecificity of the data does not allow identifying the cause of the sleep disorder in most cases, and its usefulness in this case clearly does not justify the costs. However, in some patients with severe chronic insomnia resistant to conventional treatment, the origin of which remains unclear, PSG is still indicated. In these cases, it can help to identify a primary sleep disorder that could not be diagnosed from clinical data. Establishing the correct diagnosis opens the way to more effective therapy.