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An in-depth report on the causes, diagnosis, treatment, and prevention of insomnia.

Alternative Names


Risk Factors

Studies estimate that between a quarter and one-third of American and European adults experience some insomnia each year, with between 10% and 20% of them suffering severe sleeplessness. In spite of this widespread problem, however, studies suggest that only about 30% of American adults who visit their doctor ever discuss sleep problems. Conversely, physicians seem rarely to ask patients about their sleep habits or problems.

Significant Risk Factors for Stress

A 2003 study suggested that there were seven significant factors that predicted who would be at high risk for insomnia:

  • Being older.
  • Having conflicts with relatives.
  • Being overworked on the job.
  • Being overworked at home.
  • Having a sick relative.
  • Having low social status.
  • Having a psychiatric or psychologic problem.

Negative Thinking

Stressful events do not cause insomnia in everyone. Negative thoughts and attitudes toward events can be significant factors in insomnia. In one 2003 study, for example, the number of stressful events did not differ between good and poor sleepers. Those with insomnia, however, tended to experience these stressful events more intensively than the healthy sleepers.

In another interesting study, patients with insomnia and good sleepers were asked to record their pre-sleep images using a handheld counter. People with insomnia not only reported fewer images, but their images also tended to be more unpleasant than those of good sleepers. More of the images in people with insomnia were related to intimate relationships and to sleep itself. The images of sleepers were more likely to be random and disconnected.

Having Depression, Chronic Pain, or Both

Studies report that the strongest risk factors for insomnia are psychiatric problems, particularly depression, and physical complaints, such as headaches and chronic pain, that have no identifiable cause (called somatic symptoms). About 90% of people with depression have insomnia. In addition, insomnia and depression often coincide with somatic symptoms, particularly chronic pain. In fact, insomnia worsens chronic pain even in people who are not depressed. Headaches that occur during the night or early in the morning may actually be caused by sleep disorders. In one study, patients who had these complaints were treated for the sleep disorder only, and over 65% reported that their headaches were cured.

Gender Factors

Overall, insomnia is more common in women than men, although men are not immune from insomnia. Sleep efficiency deteriorates equally in men and women as they get older.

Men. One major study suggested that as men go from age 16 to 50, they lose about 80% of their deep sleep. During that period, light sleep increases and REM sleep remains unchanged. (The study did not use women as subjects, and there is some evidence to suggest they are not as affected.) After age 44 REM and total sleep diminish and awakenings increase.

Women. It is not clear why young adult women suffer more from insomnia than young adult men. Some theories are as follows:

  • In women, a number of hormonal events can disturb sleep, including premenstrual syndrome, menstruation, pregnancy, and menopause. All these conditions are short term, however, and in most cases the wakefulness associated with them is temporary and can be ameliorated with sleep hygiene and time.
  • After childbirth, most women develop a high sensitivity to the sounds of their children, which causes them to wake easily. Women who have had children sleep less efficiently than women who have not had children. It is possible that many women never unlearn this sensitivity and continue to wake easily long after the children have grown.
  • Women are at higher risk than men are for depression and anxiety, which are known risk factors for insomnia. In fact, some researchers believe that this is predominant reason for the gender differences in insomnia.

It should be noted that after menopause women are susceptible to the same environmental and biologic causes of insomnia as men. In fact, older women who are not bothered by sleeplessness tend to have longer and better sleep than noninsomniac men their own age.

Risk Factors in Elderly Adults

As people grow older, sleep changes in most older people, and about 15% of their sleeping time is in stage 1, light sleep. (In infancy, only 5% is spent in light sleep.). In a major 2003 survey, 18% of older adults (55 to 94 years old) had trouble falling asleep. A third of them woke up frequently during the night and about a quarter of them woke up too early and couldn't go back to sleep. In the same study, 33% of adults between 55 and 64 reported waking up feeling unrefreshed, which was actually greater than the percentage reported by older people (22%).

Nevertheless, age itself does not appear to be a risk factor for insomnia. A number of factors increase sleeplessness as one gets older:

  • Elderly people are more likely to be sedentary than younger adults.
  • Medical conditions that cause pain or nighttime distress are common in the elderly and pose a high risk for insomnia. They include arthritis, gastrointestinal distress, frequent urination, lung disease, and heart conditions.
  • Neurologic diseases in the elderly, such as Parkinsons, Alzheimers, and other forms of dementia, can cause nighttime disorientation, confused wandering, and delirium.
  • Older people often take a number of prescription drugs whose side effects include insomnia.
  • The elderly are also prone to grief, depression, and anxiety, the handmaidens of sleeplessness. One study found, in fact, that in healthy older adults, psychologic factors, such as anxiety and depression, were more likely to be the cause of insomnia than illness, medications, or living conditions.
  • Melatonin levels are lower in general in older people. Some research suggests, however, that elderly people may have lower levels simply because many stay mostly indoors and out of normal sunlight.

Sleep loss among the elderly is not inevitable, however. While older people are more susceptible to many conditions that can cause insomnia, treatments and a healthy lifestyle, particularly regular exercises, are as useful in providing relief to the elderly as to the young. And a number of studies have found no significant increase in insomnia in older healthy adults.

Shift Workers

Shift workers are at considerable risk for insomnia. In one major 1999 survey, 65% of shift workers reported one or more symptoms of insomnia at least a few nights a week. Workers over 50 and those whose shifts are always changing are particularly susceptible to insomnia, although night-shift workers also have a high rate of sleeplessness.

Other Risk Factors

Among the many conditions that pose a high risk for insomnia are the following:

  • Frequent travel, particularly crossing time lines.
  • Post-traumatic stress syndrome.
  • Brain injuries.
  • Many chronic medical conditions ranging from seemingly minor ones, such as tinnitus (ringing in the ears) to major medication conditions, such as respiratory problems, heart disease, or being on dialysis.

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