Causes Chronic Insomnia

Sleep problems seem to run in families. About 35% of people with insomnia have a family history of insomnia, with the mother being the most commonly affected family member. Still, because so many factors are involved in insomnia, a genetic component is difficult to define.

Brain Chemicals and Hormones Affecting Chronic Insomnia

Abnormal levels of certain brain chemicals have been observed in some people with chronic insomnia.

• Melatonin. Low levels of melatonin, the hormone secreted by the pineal gland, have sometimes been observed in chronic insomnia.
• Stress Hormones. Some studies have reported persistently high levels of stress hormones, particularly cortisol, in people with chronic insomnia, particularly insomnia related to aging and psychiatric disorders. High levels of cortisol reduce REM sleep. However, a 2003 study of people with chronic insomnia reported that cortisol levels were high only when their sleep was of poor quality. When they slept well, levels were lower. This study and other research suggests that high levels of stress hormones are caused by poor sleep, rather than being the cause.
• Growth Hormone. Normal aging is associated with a blunting of regular, cyclical surges of growth hormone, which may affect sleep as one gets older. This hormone, which is normally secreted in the late night, is associated not only with growth but with deep, slow-wave sleep. (Older people generally have less slow-wave sleep.)

Chronic Insomnia and the Immune System

Chronic insomnia occurs in people who have persistently high levels of stress hormones and a shift in the levels of certain immune factors. Studies indicate that people with chronic insomnia have higher levels of interleukin-6 and tumor necrosis factor during the day, but lower levels at night. These immune factors, called cytokines, cause symptoms of fatigue. Levels are usually higher at night in people with healthy sleep. The implications of these immune changes in people with insomnia are not known.

Emotional Disorders

Many cases of chronic insomnia cases have a psychologic or psychiatric basis. The disorders that most often cause insomnia are:

• Anxiety.
• Depression. Sleep abnormalities are an integral part of depressive disorders, with more than 90% of depressed patients experiencing insomnia.
• Bipolar disorder.

Insomnia may also cause emotional problems. It is often unclear which condition has triggered the other, or if the two conditions, in fact, have a common source.

Psychophysiologic Insomnia

In many cases, it is unclear if chronic insomnia is a symptom of some physical or psychological condition or if it is a primary disorder of its own. In most instances, a mix of psychological and physical conditions causes the insomnia.

Psychophysiologic insomnia occurs when:

• An episode of transient insomnia disrupts the person's circadian rhythm.
• The patient begins to associate the bed not with rest and relaxation but with a struggle to sleep. A pattern of sleep failure emerges.
• Over time, this event repeats, and bedtime becomes a source of anxiety. Once in bed, the patient broods over the inability to sleep, the consequences of sleep loss, and the lack of mental control. All attempts to sleep fail.
• Eventually excessive worry about sleep loss becomes persistent and provides an automatic nightly trigger for anxiety and arousal. Unsuccessful attempts to control thoughts, images, and emotions only worsen the situation. After such a cycle is established, insomnia becomes a self-fulfilling prophecy that can persist indefinitely.

Sometimes anxiety and the inability to sleep dates back to childhood when parents used various threats to force their children into sleep for which they may not have been ready.

Medical Conditions and Treatments

In one survey, 22% of adults reported that health conditions, pain, or discomfort impaired their sleep. These conditions can include:

Nightly Leg Problems. Leg disorders that occur at night, such as restless legs syndrome or leg cramps, are of special note. They are very common and an important cause of insomnia, particularly in older people.

Medical Problems. Among the many medical problems that can cause chronic insomnia are allergies, arthritis, cancer, fibromyalgia, heart disease, gastroesophageal reflux disease (GERD), hypertension, asthma, emphysema, rheumatologic conditions, Alzheimer's disease, Parkinson's disease, hyperthyroidism, and attention deficit hyperactivity disorder.

Medications. Among the many medications that can cause insomnia are antidepressants (fluoxetine, bupropion), theophylline, lamotrigine, felbamate, beta-blockers, and beta-agonists.

Alcohol Overuse

An estimated 10 -15% of chronic insomnia cases result from substance abuse, especially alcohol, cocaine, and sedatives. One or two alcoholic drinks at dinner, for most people, pose little danger of alcoholism and may help reduce stress and initiate sleep. Excess alcohol or alcohol used to promote sleep, however, tends to fragment sleep and cause wakefulness a few hours later. It also increases the risk for other sleep disorders, including sleep apnea and restless legs. Alcoholics often suffer insomnia during withdrawal and, in some cases, for several years during recovery.

Shift Work and Chronic Insomnia

Shift work throws off the body's circadian rhythm and may lead to chronic insomnia.