Sleep and Its Abnormalities

10.1 Shortened Sleep Duration and Abnormal Sleep–Wake Rhythm

10.3 Hypersomnia and Excessive Daytime Somnolence

10.4 Abnormal Movements in Sleep (Parasomnias)

Restful? Not Quite

The patient, a 50-year-old chef and restaurateur, proprietor of a popular establishment amid the old-town arcades of the Swiss capital, often worked from early in the morning till late at night. His heavy workload and the constant temptations around him had led to steadily increasing alcohol consumption over the last few years. Though already obese, he had put on a good deal more weight. His employees respected him and liked him for his jovial, enthusiastic manner, but they noticed that he had become irritable and impatient in recent months. He had also become slower and less concentrated in his work; ever more frequently, a meal emerged burnt from the oven or a soup was spoiled with too much salt. One afternoon, the staff even caught him taking a nap on a chair in the kitchen. This began to happen with increasing regularity.

The patient himself was very worried and consulted his family physician, telling him about the embarrassing happenings in the restaurant. Asked about his sleep habits, he said he had often, in recent months, woken up from sleep with a start and found himself covered in sweat. He had the feeling of having woken up from a nightmare but could not remember dreaming. He was now getting up with a headache and a dry mouth every morning, and he felt exhausted all day long.

Sleep can be disturbed in many different ways. Difficulty falling asleep and difficulty staying asleep are very common; abnormal behavior during sleep and daytime somnolence can occur as well. Thorough history-taking with specific questioning, not just of the patient, but also of his or her bedmate and other family members, often brings the underlying cause to light. Sometimes, however, the diagnosis can only be established by further evaluation, including polysomnography (PSG; a “sleep study”), nocturnal oximetry, and video observation of the sleeping patient with an infrared camera.

He was obviously suffering from a marked sleep disturbance with excessive daytime somnolence. The family physician called his wife in to ask her a few questions and clarify the situation. She said her husband had always been a snorer, but his snoring had gotten louder over the past 2 years or so. Lately, he had often temporarily stopped breathing during sleep; this worried her very much. The pauses in breathing usually lasted several seconds and were then followed by a deep sigh, as if he were gasping for air. On a few occasions, he had stopped breathing for such a long time that she panicked and shook him awake, because she was afraid he might die.

This patient’s symptoms and the clear history given by his wife led to the diagnosis of sleep apnea syndrome. Nocturnal oximetry revealed as many as 25 desaturations per hour, sometimes to values below 80%. The doctor urgently advised him to lose weight and to give up alcohol entirely, because overweight and alcohol both contribute to the pathogenesis of the syndrome. He also told him to avoid sleeping on his back. Because of daytime somnolence in particular, the patient was given a biphasic positive airway pressure (BIPAP) device. He tolerated it poorly at first, but his symptoms then improved so much that he became a devoted user. After the first night of successful BIPAP therapy, he was no longer sleepy during the day. He lost 8 kg of weight over the next 3 months.

Key Point

The individual sleep requirement is genetically determined: it varies from 4 to 11 hours per night, with an average of 7 to 8 hours. The body’s “internal clock” has an intrinsic “day” lasting somewhat longer than 24 hours and needs to be continually reset by external stimuli to keep pace with the environmental day/night cycle. This sensitive process can be impaired by various exogenous factors and diseases. The resulting disturbances are best classified by their main clinical features: disturbances of sleep duration and the sleep–wake rhythm, insomnia, hypersomnia, excessive daytime somnolence, and special abnormal phenomena occurring during sleep (parasomnias).

10.1 Shortened Sleep Duration and Abnormal Sleep–Wake Rhythm

Note

The patient sleeps too little, falls asleep too late, or wakes up too early. Often, the problem is an organic or psychological disturbance affecting the ability to fall asleep and/or stay asleep, or an abnormal setting of the internal clock.

If the patient sleeps too little at night, the most common cause is simply that the patient’s social environment prevents adequate sleep. Pathologic causes include somatic conditions (e.g., pain), internal medical illnesses, psychosocial problems or conflicts, and endogenous depression. These usually lead to difficulty falling asleep, staying asleep, or both.

If the patient falls asleep much too late and tends to sleep for a long time in the morning, the internal clock is incorrectly set. This is called the delayed sleep phase syndrome and is most common among adolescents.

10.2 Insomnia

Key Point

Insomnia is now defined as a condition in which the patient finds that he or she does not get enough sleep and that the normal restorative benefit of sleep is lacking. Insomnia can occur as a primary disorder or as a consequence of many different environmental situations and physical and mental illnesses. Patients with restless legs syndrome (RLS) complain of abnormal sensations in the limbs and an abnormal urge to move them, often in combination with difficulty falling asleep.

10.2.1 General Principles

Insomnia can be divided into difficulty falling asleep, difficulty staying asleep (often called “sleep continuity disturbance” in the specialized literature), and early morning awakening. Sleep can also be subjectively inadequate, even if its quality and duration seem adequate when objectively assessed. Insufficient nighttime sleep can lead to daytime somnolence, exhaustion, and depression. The evaluation of insomnia should include a search for contributory extrinsic factors (noise, shift work, jet lag, etc.), physical and mental illnesses, and substances that can impair sleep, such as alcohol, caffeine, steroids, and stimulant drugs (both licit and illicit).

Treatment If an underlying disease is found, the treatment of insomnia begins with the treatment of the disease. Behavior changes, such as proper sleep hygiene, the elimination of exogenous disturbances, getting to bed on time, and the use of relaxation techniques, are a further major component of treatment. Sedatives can be used as well; the choice of drug depends on the underlying problem. Benzodiazepines should be used only to treat acute insomnia, and for no more than a few weeks’ time, for example, for a student who cannot sleep because of impending examinations.

10.2.2 Restless Legs Syndrome

About 20% of patients with insomnia suffer from RLS. They complain mainly of difficulty falling asleep.

Note

Patients with RLS suffer from a distressing urge to move the legs that is worst toward the evening when they sit in a relaxed position or lie in bed and that improves with mental or physical activity. Most patients actually do move their legs whenever they sit or lie down. To gain relief, they sometimes need to get up and walk around.

Epidemiology The prevalence of RLS increases with age; it is 5 to 10% overall. Women are twice as commonly affected as men.

Etiology and pathogenesis Primary RLS is usually idiopathic; in other words no specific cause can be found. One-third of patients, particularly those who develop the syndrome when young, have this disorder as a familial condition with autosomal dominant inheritance. Mutations are found at various genetic loci.

Secondary RLS can be due to iron deficiency, renal insufficiency, hypothyroidism, spinal cord lesions, polyneuropathy, pregnancy, or drugs (licit and illicit) such as neuroleptic drugs, antiemetic drugs (exception: domperidone), tricyclic antidepressants, selective serotonin reuptake inhibitors, and ecstasy.

The pathogenesis of RLS is not fully clear. The dopaminergic and endogenous opioid systems and the body’s iron metabolism all appear to be involved.

Definition, clinical features, and diagnostic evaluation RLS is defined by the following criteria:

Urge to move the limbs and abnormal sensations (such as burning or tingling) in the limbs; symptoms mainly but not exclusively in the lower limbs.
Worsening of symptoms at rest (lying down, sitting).
Improvement of symptoms with mental or motor activity (concentration, walking around).
Worst symptoms in the evening or at night.

Confirmatory criteria include a positive family history, periodic leg movements in the night (particularly in the superficial stages of sleep), and response to treatment with dopaminergic drugs. RLS may cause daytime fatigue and irritability because of the lack of sleep. The neurologic examination is normal in patients with idiopathic RLS.

The diagnosis is usually made on clinical grounds alone. L-dopa can be given to test responsiveness to dopaminergic treatment. The additional diagnostic evaluation, serving mainly to exclude the possible causes of RLS, includes the following:

Laboratory testing, for example, to exclude iron deficiency, renal insufficiency, or hypothyroidism.
Electromyography and electroneurography to detect or rule out polyneuropathy.
PSG, for example, in children with pronounced RLS, or if respiratory problems during sleep are suspected.

The differential diagnosis includes polyneuropathy, hypnagogic myoclonus, akathisia, and the so-called painful legs and moving toes syndrome.

Treatment The treatment usually consists of nonpharmacologic measures, for example, mental activity (distraction), light exercise, abstinence from coffee and alcohol, and sleep hygiene. If RLS is secondary to another disorder, the underlying disease should be treated, for example, with iron supplementation or the discontinuation of the drugs that are causing the problem. Only one-third of patients need drugs to treat the syndrome; the agents of choice are dopamine agonists such as ropinirole, pramipexole, and rotigotine, initially in combination with domperidone to prevent nausea (if necessary). Sometimes these treatments worsen the condition instead of improving it (“symptom augmentation”). In such cases, an anticonvulsant such as gabapentin or pregabalin or an opioid such as codeine or tramadol can be given. L-dopa, with or without a decarboxylase inhibitor, leads to symptom augmentation more commonly than the dopamine agonists do and is thus only rarely given to treat RLS.