Risk Factors
Studies estimate that between 25 - 33% of adults experience some insomnia each year. In spite of this widespread problem, however, studies suggest that only about 30% of American adults who visit their doctor ever discuss sleep problems. And, doctors seem rarely to ask patients about their sleep habits or problems.
Seven Significant Risk Factors
A 2003 study suggested that there were seven significant factors that predicted 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. However, negative thoughts and attitudes toward events can be significant factors in insomnia. In one 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 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.
Depression and Chronic Pain
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. A study presented at the 2005 Associated Professional Sleep Societies meeting indicated that insomnia may contribute to, and prolong, depression. Researchers analyzed data from over 1800 adults aged 65 years and older. Compared with depressed patients who did not have sleep problems, depressed patients with insomnia were 11 times more likely to remain depressed after 6 months and 17 times more likely to still be depressed after a year. The researchers suggested that treating insomnia may help patients recover from depression more quickly.
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.
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