While we don’t fully understand what causes insomnia, we do know that it’s affected by both the body (physiology) and the mind (psychology). People with insomnia differ from good sleepers in both of these areas. For example, recently developed technology allows us to observe the brain activity of people as they sleep. By comparing the brains of good and poor sleepers during their sleep, researchers at the University of Pittsburgh have shown that people with insomnia continue to have high activity in areas of the brain that normally are “quieter” during sleep (Nofzinger et al. 2006). In the same vein, sophisticated research studies have allowed researchers to tap into psychological differences between good and poor sleepers. For example, researchers in Glasgow, Scotland, found that people with insomnia more readily pay attention to images related to sleep than images that aren’t related to sleep (Espie et al. 2006). They also respond more quickly to pictures related to sleep than those without insomnia, suggesting that they’re more focused on items related to sleep than people without insomnia. In both examples, it’s not clear whether the observed differences initially caused or are caused by insomnia. However, in both cases, hyperactivity in the brain or hyperattention to sleep-related material would seem to worsen and perpetuate the insomnia. One thing that’s clear is that there’s a delicate balance between things that make sleep more likely (sleep-promoting factors) and things that make wakefulness more likely (alertness-promoting factors). Insomnia occurs when alertness-promoting factors predominate over sleep-promoting factors. What follows is a brief review of some physiological and psychological sleep-promotingand alertness-promoting factors that have been studied in insomnia.

Physiological Factors in Insomnia:

As stated earlier, the exact physiologic causes of insomnia are currently unknown. A variety of chemicals in the brain, such as adenosine, melatonin, orexin, cortisol, and serotonin, are thought to be involved in the regulation of sleep (España and Scammell 2004). The media and advertisements for insomnia medications often use the nonspecific term “chemical imbalance” to explain the physiological aspect of insomnia. In essence, the argument is that either there’s too much of an alertness-promoting chemical or too little of a sleep-promoting chemical during the intended sleep period. Such vague terminology leads some to the conclusion that their insomnia won’t resolve unless the imbalance is chemically corrected with a medication, but this is an oversimplification. A given sleep medication may work for some people but not others. In reality, both physiological and psychological processes affect the chemicals involved in sleep regulation. Insomnia also appears to run in some families, suggesting genetic transmission, although the specific genes involved in this transmission haven’t been identified (Watson et al. 2006). Another explanation for the fact that insomnia runs in families is that insomnia may be learned; that is, perhaps the family environment promotes insomnia. For example, you might learn from your parents to be overly concerned about sleep loss, and this exaggerated concern about occasional sleep problems makes your sleep even worse. We return to this line of thought in chapter 7.Lastly, people with insomnia have higher metabolic levels (more chemical activity) during the day as well as during the night (Bonnet and Arand 1995), and their brain waves during sleep have higher frequency activity than those of good sleepers (Nofzinger et al. 2006). Both higher metabolic rates and faster-frequency brain waves suggest that people with insomnia are more highly physically activated (they have more alertness-promoting factors) than good sleepers. Remember that we don’t know whether these differences cause insomnia, because it could also be true that having insomnia causes these physiological differences.

Psychological Factors in Insomnia:

Thoughts, behaviors, and reactions to stress and daily hassles can cause and maintain insomnia. How you think about sleep and what you do to cope with sleep loss appear to play important roles in the insomnia experience. In subsequent chapters we discuss many examples that demonstrate how thoughts and behaviors interfere with sleep. But briefly, relative to good sleepers, people with insomnia have more anxious thoughts and negative emotions just before sleep and on awakening from sleep (Harvey and Farrell 2003). Anxious thoughts and negative emotions promote alertness rather than sleep, and thus can be a factor in insomnia.

excerpt from Quiet Your Mind and Get to Sleep: Solutions to Insomnia for Those with Depression, Anxiety or Chronic Pain by Colleen E. Carney Ph.D. and Rachel Manber Ph.D.