How Insomnia Works

Insomnia Causes and Risk

Not all insomnia is created equal -- there are different types of this sleep disorder, and there are differing durations, too.

There are two basic types of insomnia: primary or secondary. Primary insomnia means your problem sleeping (or staying asleep) isn't being caused by something else, like another health condition. Within this type of insomnia there are three main sub-categories: psychophysiological, idiopathic and paradoxical. Psychophysiological insomnia is based in worry -- specifically, worry about sleep, with anxiety increasing around (you guessed it) bedtime. Psychophysiological insomniacs may have a single sleepless night but worry themselves into several more of the same. Idiopathic insomnia stands apart because this type develops early in life and continues to be a lifetime sleep disorder that may (or may not) get worse with stressful events in your life. Paradoxical insomniacs are, as the name would suggest, a bit of a paradox, because this group experiences from severe sleeplessness without other symptoms such as daytime drowsiness.

While primary insomnia is its own manifestation, secondary insomnia is insomnia that's a symptom of another problem -- and about 80 percent of all insomnias are secondary [source: NHLBI]. Stressful events (such as a divorce or losing your job) may be to blame for some, as are jet lag and other shifts to your schedule. Individuals with low incomes and people who live sedentary lifestyles are also at higher risk. Additionally, insomnia may be caused by a mental health condition. Depression, anxiety and bipolar disorder, among others, are known to disturb many people's sleep patterns -- as many as 85 percent of people who have major depression also have insomnia [source: Cleveland Clinic].

Certain medications also may keep you up at night -- for example, common prescriptions known to cause insomnia in some people include drugs to treat allergies, cardiovascular disease, asthma, pain and depression, among others, and include alpha blockers (to treat high blood pressure), beta blockers (used to treat a variety of things from hypertension to migraines to heart disease), ACE inhibitors, ARBs, corticosteroids, H1 antagonists, glucosamine, statins and, ironically for those with depression-induced insomnia, SSRI antidepressants [source: Neel].

You're at risk for insomnia; we all are. One out of three adults has occasional bouts with acute insomnia, and one in 10 with chronic [source: NHLBI]. But some of us are more likely to experience sleeplessness than others. Women, for example, are more likely than men, infants and kids to have insomnia; hormonal shifts are thought to contribute to the problem. (In fact, during pregnancy, as many as 84 percent of women report symptoms of insomnia [source: Paul].) Seniors over age 60 also have an increased risk.