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Insomnia: Overview and Risk Factors

Insomnia is characterized by difficulties in initiating sleep, maintaining sleep, or feeling restored after sleep. It is the most common sleep disorder in the United States, affecting about one-third of adults at some point in their lives. Approximately 10% of those with symptoms experience persistent insomnia.

Patients often report impairments in daytime function in addition to the nocturnal symptoms. They may experience daytime fatigue, inability to concentrate, irritability, anxiety, depression, and forgetfulness, and may have an increased risk of automobile accidents.1 Further, these patients often have associated psychosomatic symptoms, such as nonspecific aches and pains.

Insomnia has been described as transient (less than 1 week of symptoms), short-term (1-3 weeks), and chronic (longer than 3 weeks).2 Dozens of possible etiologies may explain each type. Sleep impairment lasting only a few days to a few weeks may be the result of poor or altered sleep environments, such as excessive noise or light and unpleasant room temperature. It may result from lifestyle changes, such as jet lag, change in work shift, acute illness, and stressful life events. Also, taking medications with stimulant properties (eg, bronchodilators, theophylline, antidepressants, caffeine-containing pain relievers, methylphenidate) and withdrawal from drugs or alcohol may contribute to impaired sleep. Insomnia lasting more than a few weeks may be associated with chronic drug or alcohol abuse, medical disorders, or psychiatric disorders, or it may result from primary sleep disorders, such as restless legs syndrome and sleep apnea.

Risk Factors

Insomnia occurs disproportionately in women and in people who are divorced, widowed, or separated. Additional risk factors include:

Age. Prevalence increases with age. Age is the most important risk factor for developing insomnia.

Psychiatric comorbidities. Sleep disturbances are more common in patients with mood disorders such as major depression, dysthymia, and bipolar affective disorder, as well as in those with anxiety disorders, schizophrenia, and acute stress.

Drugs and alcohol. Abuse of these agents may be associated with impaired sleep.

Stimulants. Use of medications and other substances with stimulant properties is a common cause of insomnia. These include caffeine, theophylline, corticosteroids, thyroxine, and bronchodilators.

Nicotine withdrawal is associated with sleep fragmentation. Insomnia is also a frequent side effect of nicotine patches3 and of bupropion, an antidepressant often used for smoking cessation.4


Insomnia: Diagnosis and Treatment >>