[Editor's note: This article is from 2007. Some newer treatments and current statistics are not included here. See further information on BrainWeb]
sections include:evaluating sleep disorders, primary insomnia, sleep apnea, circadian rhythm disorders, nocturnal myoclonus and restless legs syndrome, parasomnias
Sleep is essential to our lives, and it’s one of the few activities we do for large parts of the day from infancy through old age. Many people, however, suffer some form of sleep disturbance troubling enough to send them to their physicians. The most common complaints involve getting too little sound sleep, feeling excessively sleepy, or having disturbances or difficulties during sleep, such as sleepwalking (somnambulism). These are not trivial problems. If you have ongoing disorders of sleep and wakefulness, you are clearly at risk for poor health and impaired occupational, social, and psychological functioning.
The symptoms of insomnia and excessive daytime sleepiness can arise from several different disorders, each of which requires specific evaluation and treatment. Before discussing these possibilities, however, we will describe how people normally sleep.
The brain has three major states of activity and function: wakefulness, rapid eye movement (REM) sleep, and non-REM (NREM) sleep. It’s during REM sleep, identifiable because the sleeper’s eyes can be seen shifting quickly below his or her eyelids, that we have our most vivid dreams. In this state, your brain becomes electrically and metabolically activated; in fact, electroencephalographic (EEG) readings during REM sleep would be somewhat similar to those recorded when you are awake. At the same time, the brain automatically stills your muscles. Even though you may be dreaming vividly, you cannot normally react to that mental activity.
Healthy sleep consists of recurring cycles, 70 to 120 minutes long, of NREM and REM sleep. Typically, a sleeping person proceeds from wakefulness through the four stages of NREM sleep until reaching the first REM period. The sleeper then returns to NREM sleep, and the cycle begins again. In healthy adults, the deepest stages of sleep—NREM stages 3 and 4, or “slow-wave sleep”—occur predominantly in the first two cycles. The REM periods in the first half of an adult’s sleep period are brief; they get longer in later cycles. Ideally, you should be able to sleep well through these cycles on a regular basis.
Evaluating Sleep Disorders
Diagnosing conditions that affect how a person sleeps starts with taking a thorough medical and psychiatric history. The doctor should look into what that individual experiences over the entire 24-hour day, not just during the nighttime. The impact of disrupted sleep on daytime mood, fatigue, muscle aches, attention, and concentration may be significant. Often doctors ask people to keep a two-week log recording their sleep-wake patterns; napping and activity during the day; use of stimulants, hypnotics, or alcohol; diet; number of times they wake during the night; how long they think they have slept; and how they perceive their daytime mood and alertness.
Only about 4 percent to 5 percent of the general population complains of being too sleepy during the day. A much larger percentage complains of insomnia, or not being able to fall asleep at night. Nevertheless, over half of the people referred for formal sleep studies have symptoms of excessive sleepiness, especially a propensity to nod off. The severity of this problem is called mild if a person falls asleep during a sedentary activity, such as watching television; moderate if a person drifts off during mild physical activity, such as driving; and severe if sleep occurs during a physical activity that requires moderate attention, such as talking or eating. Obviously, falling asleep at the wheel of your car is much more hazardous than falling asleep during a conversation, and doctors take that symptom very seriously. But nodding off while talking actually indicates a more severe disorder because that activity engages more of your brain at once.
Doctors usually ask sleepy individuals about such symptoms as morning headaches; cataplexy (loss of muscle strength triggered by strong emotions); hallucinations during drowsy periods; sleep paralysis; finding one has done tasks during sleep without remembering them; and feeling confused or disoriented during the transition between sleep and being awake (called sleep drunkenness). Doctors also often interview bed partners about behavior that a sleeping person cannot perceive, such as snoring, respiratory pauses longer than ten seconds, unusual body movements, and sleepwalking. If you complain of disturbances during sleep, expect questions about nocturnal incontinence, sudden episodes of troubled breathing, headaches, jaw clenching or teeth grinding (bruxism), talking in your sleep, and sleepwalking.
All-night sleep recordings, or polysomnography, remain the principal diagnostic tool in the field of sleep medicine. A thorough test provides data on an individual’s periods of uninterrupted sleep, REM and NREM stages, breathing patterns, oxygen levels, heart rhythm, and movements. Doctors may also want to monitor body temperature and whether a man has erections while asleep. This test usually requires spending one night in a sleep clinic. If you are excessively sleepy, polysomnography is well justified given your high risk of having sleep apnea or narcolepsy. Doctors may also use polysomnography for anyone with other problems they suspect are related to sleep apnea or nocturnal seizure disorder. Polysomnography is generally not used to evaluate chronic insomnia except when doctors suspect the root cause is an undetected, or occult, sleep disorder like sleep apnea or nocturnal myoclonus, or involuntary muscle contractions.
Primary insomnia is the medical term for difficulty falling asleep, remaining asleep, or waking up feeling unrefreshed for over a month. By definition, primary insomnia must result in significant daytime impairment and not be connected to another sleep disorder.
For some people, this condition lasts a lifetime. These individuals have a constitutional predisposition for fragmented sleep. We do not know the reason, but the condition probably stems from a neurochemical or structural disorder involving the neural networks that govern our sleep-wake states. People with this disorder are extremely light sleepers, easily perturbed by noise, temperature fluctuations, and anxiety.
Some people develop primary insomnia following a period of severe stress. For these individuals the difficulty going to sleep lingers after the source of stress has been removed because they have adapted new behaviors that disrupt sleep. Often they have come to associate cues in their sleeping environment, such as clocks, with being awake, thus reinforcing the sleep disturbance. This disorder can persist over many years and cause chronic fatigue, muscle aches, and mood disturbance.
Treatment for insomnia often involves education about healthy sleep practices and an examination of behaviors that may interfere with sleep. Individuals may be instructed to improve their sleep hygiene by maintaining a regular bedtime, avoiding alcohol and caffeine, getting regular exercise, and avoiding stressful activity before retiring. Such relaxation therapies as meditation, deep breathing, and progressive muscle relaxation can be helpful. It is often beneficial for people to modify their behavior so they don’t spend much time awake in bed. This allows them to associate lying down in bed with sleeping. These are all effective treatments for insomnia that do not involve the use of sleeping pills.
Treating chronic insomnia with sleeping medications remains controversial, particularly for the elderly. Sleeping medication should be considered only after doctors have thoroughly assessed the possible causes of the insomnia that may be treated in other ways, and after sleepers have tried to improve their sleep through behavioral changes. If those steps are unsuccessful, then doctors may prescribe hypnotics, starting with very low doses for short, limited periods. Sleeping medications such as zolpidem, zaleplon, and short and intermediate half-life benzodiazepines are safe and effective in treating transient insomnia in people who have not had problems with substance abuse.Sleep Apnea
People with sleep apnea frequently stop breathing during sleep. This makes the oxygen levels in their blood drop, and they may wake up gasping loudly and thrashing. Though EEG readings would show these people’s brains reach a wakeful state, they usually return to sleep quickly and do not remember the interruption. They simply feel a lack of refreshing sleep in the morning. Often, alarmed bed partners alert people with sleep apnea to the problem, and their observations of the sleeping subject are very useful to doctors. Although it occasionally causes insomnia, sleep apnea is typically an occult disorder that causes daytime sleepiness, impaired concentration and intellectual functioning, and morning headaches. Sleep apnea is associated with obesity and loud snoring, and it seems to be connected to high blood pressure, irregular heartbeat, and early death. Sleep apnea is also related to age: it affects approximately 24 percent of people over the age of 65 and 42 percent of the elderly living in nursing homes.
There are a variety of treatments for sleep apnea. People often benefit from losing weight, abstaining from sedative-hypnotic drugs, and learning to avoid sleeping on their backs. Mechanical approaches include devices to hold down the tongue or pull the jawbone forward, both of which help keep the airway clear. Continuous positive airway pressure (CPAP) is the treatment of choice for moderate to severe sleep apnea. The sleeper wears a device over his or her nose and mouth that blows air into those orifices, causing the mouth and throat to remain open for every breath. For severe cases, surgical techniques to increase the size of a person’s airway include reshaping the inner structures of the mouth and throat (uvulopalatopharyngoplasty), shifting the bones of the jaw area (maxillomandibular and hyoid advancement), and chronic tracheostomy.
Circadian Rhythm Disorders
The timing of our daily sleep-wake cycle is mainly under the control of the suprachiasmatic nucleus in the hypothalamus, which establishes a daily, or circadian, rhythm. This rhythm can be disrupted by external demands on us to be awake at particular times. Circadian rhythm sleep disorders show up as either insomnia or excessive sleepiness, depending on when a person’s body thinks it is in the sleep or wake cycle. Travelers flying across multiple time zones and rotating shift workers can experience fatigue, gastrointestinal upset, and other physical symptoms because of disruptions of their circadian rhythms. Some studies have shown that people with disrupted circadian rhythms also think less effectively and less quickly.
The treatment for many circadian rhythm disorders involves realigning a person’s sleep-wake schedule by manipulating or augmenting the external environmental cues our bodies rely on. One example is bright light therapy. Many studies have shown that exposure to bright light can shift and realign people’s circadian rhythms.
Some individuals have circadian rhythm disorders related to a diminished capacity to respond to environmental cues about when to sleep, especially the natural daily cycle of light and dark. People with the delayed sleep-phase disorder seem to have an innate preference for beginning to sleep in the late hours of night and staying in bed until late morning or early afternoon. If such “night owls” can find work and social life that fit that schedule, of course, their preference stops being a disorder.
Nocturnal Myoclonus and Restless Legs Syndrome
Nocturnal myoclonus, or “twitching at night,” is characterized by periodic leg movements that interrupt a person’s sleep. People are usually unaware of this disorder except as morning leg cramps and a sense of insufficient sleep. They may complain of either insomnia or daytime sleepiness. Nocturnal myoclonus is a relatively common disorder that frequently appears in association with sleep apnea, narcolepsy, uremia, diabetes, and a variety of disorders affecting the cortex, brain stem, and spinal cord. Typically, however, it has no obvious cause and no link to larger problems in the central nervous system.
Restless legs syndrome is another disorder that prevents people from falling asleep. A person feels discomfort in his or her calf muscles and an urge to keep the legs in motion. This condition is associated with uremia, anemia, and pregnancy, as well as with nocturnal myoclonus.
The most common treatments for both nocturnal myoclonus and restless legs syndrome involve medications. Specifically, physicians prescribe benzodiazepines, dopaminomimetics such as L-dopa and bromocriptine, or other drugs that increase the brain’s supply of the neurotransmitter dopamine. Other medications currently under investigation include opioids and anticonvulsants.
Parasomnias are adverse events or behaviors that occur during sleep. Sleepwalking and sleep terrors both involve incomplete awakenings that generally occur when individuals are in the deepest stages of NREM sleep: stages 3 and 4. Sleepwalking and night terrors are normally experienced by young children, though in some cases these problems may persist into adulthood.
Sleepwalkers become partially aroused and start to move around their homes. They are typically difficult to fully awaken and do not remember their activity. They are frequently clumsy and occasionally hurt themselves during these episodes.
Sleep terrors involve the emergence during sleep of intense fear and its normal autonomic symptoms—sweating and increased heart rate, for instance. The people who suffer these terrors are inconsolable, difficult to fully awaken, and unable to recall the specific thoughts or images that made them anxious. In contrast, children (or adults) who suffer nightmares are usually able to remember their anxiety-provoking dreams in vivid detail.
Normally our muscles do not work when we are in REM sleep, but in rare cases that off switch does not work. The term REM behavior disorder refers to prominent motor activity during dreaming. Several dramatic cases have involved patients who suddenly assaulted their bed partners in response to frightening dreams. REM behavior disorder can appear during periods of drug intoxication or withdrawal, or be a chronic condition, most typically in people with a clear neurological disease.
Treatment for parasomnias is directed toward reducing sleep deprivation, stress, and anxiety, all of which are known to exacerbate these disorders. When families can identify sources of stress or anxiety, psychotherapy is usually helpful. Children may also benefit from changing their behavior (maintaining regular sleep hours, perhaps including naps) or from more specific behavioral techniques (such as hypnosis, or awakening the child at appropriate times to preempt episodes). In extreme cases, low-dose benzodiazepines are effective. For patients with REM behavior disorder, doctors have found that benzodiazepines, such as clonazepam, and the anticonvulsant carbamazepine are useful in reducing the troubling episodes.
back to top