Causes of 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.

Anxiety, Depression, and Other Mental Health Disorders

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

• Anxiety
• Depression
• Bipolar disorder
• Attention-deficit hyperactivity disorder
• Post-traumatic stress disorder
• Brain injuries

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. [For more information, see In-Depth Reports #28: Anxiety; #08: Depression; #66: Bipolar disorder; #30: Attention-deficit hyperactivity disorder.]

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:

• 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.

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. [See In-Depth Report #95: Restless legs syndrome.]

Medical Problems and Their Treatments

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, epilepsy, and fibromyalgia. Many patients with chronic pain also sleep poorly.

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

Substance Abuse

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.