The Introduction To Insomnia

A people who sleeps 6 to 7 hours may be concerned that she or he is not sleeping long enough or having insomnia, not realizing that 6 to 7 hours is currently the population average. Many people believe that 8 hours of sleep is required for health, and not having an insomnia, but there is little medical basis to recommend sleeping 8 hours or more. For example, a classic study found that long sleepers reported less energy and had more psychopathology than did short sleepers.

Insomnia is not synonymous with short sleep. Patients commonly complain of insomnia when their sleep durations are well within the range of those people without sleep symptoms. A patient may be concerned by a 20-minute latency to fall asleep, or by awakenings during the night, or by early awakening, when many people with the same sleep latencies and awakenings consider their sleep perfectly satisfactory. Sometimes, such complaints arise from misinformation about what sleep pattern is normal for a person's age.

At other times, sleep complaints may reflect a negative self-view and the somatic concerns arising from depression. Insomnia complaints are common symptoms of depression and a large variety of other emotional and medical co morbidities that may not entail particularly short sleep. Indeed, in the presence of sleep complaints, physicians make a diagnosis of depression more often than a diagnosis of insomnia.

Epidemiology can inform us what sleep patterns are associated with the lowest mortality risk. In 1959 to 1960, the Cancer Prevention Study I (CPSI) gave health questionnaires to more than 1 million adult Americans who were followed up prospectively for 6 years. The lowest mortality was experienced by women and men who reported sleeping 7 hours. More excess mortality was associated with sleep durations of 8 hours or more than with sleep of less than 7 hours. 

Excess mortality associated with long sleep has also been observed in smaller prospective studies. The CPSI results indicated little if any association of "insomnia" with mortality. In contrast, reported "sleeping pill" use "often" was associated with statistically robust increased mortality risk after control for insomnia.

A more recent study, the Cancer Prevention Study II (CPSII) of the American Cancer Society, offered an opportunity to consider whether sleep durations, insomnia, or sleeping pill use predicts mortality after more extensive control for various sources of co morbidity.