Sleep disturbance: epidemiology

Epidemiology of sleep disorders

The prevalence of sleep disorders and complaints of poor sleep has been the subject of several studies. Surveys conducted in the US, European countries and Australia showed that between 30 and 40% of adults report sleep disturbances, or at least some degree of dissatisfaction with sleep, that occurred during the preceding year. For example, a study of 3000 adults in the US, conducted in 1985, found insomnia in 35% of cases, with 17% of those surveyed having a marked or persistent insomnia (Mellinger et al., 1985). It is noted that 85% of people with severe, persistent insomnia did not receive any treatment.

The National Sleep Research Foundation of the United States and the Gallup Institute conducted a survey of 1,000 and 1,027 individuals in 1991 and 1995 to determine the frequency and nature of sleep disorders. The results of these surveys were, on the whole, comparable and contained a number of important and interesting observations. Like previous studies, surveys have shown that from one-third to one-half of the adult population, at least episodically, problems with sleep are noted. And 9-12% of the respondents suffered from insomnia systematically or often. The 1995 survey also showed that adults with severe sleep disorders are less likely to assess their overall health. Of course, this relationship can be explained in different ways:

1. poor sleep quality can indeed have an adverse effect on physical health;
2. people with chronic sleep disorders are more likely to assess health more negatively;
3. poor physical health has an adverse effect on the quality of sleep.

Daytime sleepiness was noted in 40% of adults, and 12% of respondents said they could doze off during the daytime activity. It is curious that only 30% of adults with sleep disorders discussed this problem with doctors or other public health workers. Moreover, people with sleep disorders rarely write to the doctor for this. In a separate study, it was noted that only half of the general practitioners asked the patient in detail about the state of sleep, even after he complained of a bad dream. Thus, the obtained data testify, on the one hand, about the widespread prevalence of sleep disorders, and on the other hand, that they are poorly recognized and treated.

Although insomnia is the most common sleep disorder, when evaluating the prevalence of sleep disorders, you should also keep in mind some other conditions. Although insomnia is widely represented, it is necessary to distinguish it from other sleep disorders, for example, obstructive sleep apnea. Obstructive sleep apnea, described in the early 1970s, is a disorder that is quite widespread among adults, associated with a high risk of a number of diseases and increased mortality. In one of the epidemiological studies (Wisconsin Sleep Cohort Study) it was noted that obstructive sleep apnea is detected (in accordance with very strict criteria) in 2-4% of the adult population.

Although the prevalence of narcolepsy is relatively small (in the US there are 125-250 thousand patients), it is a very serious health problem due to chronic course and adverse effects on the life of patients.

Periodic limb movements in a dream (PDS) are another important disorder. Although its exact prevalence is difficult to assess, it is known that it increases with age. According to a Gallup poll of 1995, 18% of adults report significant movements or twitching of their legs during sleep.

Another group of sleep disorders is associated with a violation of the sleep and wake cycle (circadian rhythm disorder). For example, poor sleep quality and daytime sleepiness are found in 26% of men and 18% of women employed in shift work. The change of time zones is also a frequent cause of poor sleep and daytime sleepiness. Given that modern production is becoming more complex, in the future, it is possible to predict the increase in the prevalence of this kind of occupational sleep disorders.

[1], [4], [6], [7], [8], [9], [10], [11], [12], [13]

Consequences of sleep disorders

The impact of sleep disorders on overall health, quality of life and various economic indicators was evaluated in several studies. Knowing the high physiological significance of sleep, one can assume that its disturbances will have a significant impact on the state of health. Nevertheless, it is difficult to assess the consequences of sleep disorders, although there is a number of evidence that poor sleep quality is fraught with serious complications. It has already been mentioned that, in a Gallup poll of 1995, people with chronic sleep disorders generally assessed their physical condition lower than those without irregularities or with mild sleep disorders. In other studies, it was noted that insomnia adversely affected a number of aspects of the quality of life: for example, a sense of satisfaction with life, relationships with others, professional activity. In studies on the impact of sleep disturbances on industrial activity, a link between sleepiness and frequent absenteeism, a decrease in working capacity and quality of work, an increase in the number of accidents. Accidents on transport are of particular importance for health care. Persons suffering from insomnia are 2-3 times more likely to get into traffic accidents. According to a 1995 Gallup poll, 31% of adults reported experiencing drowsiness at the time of driving. Moreover, approximately 4% of the respondents reported that they got into a traffic accident because they fell asleep at the wheel.

A number of studies have attempted to link insomnia with various diseases. It turned out that insomnia is associated with an increased risk of heart disease, hypertension, stroke and diabetes. It was proved that in patients with obstructive sleep apnea, the risk of hypertension and stroke increased. Reported a higher mortality in people with insomnia. Nevertheless, it remains unclear whether these links have a causal nature. In connection with this, additional studies are needed on the effect of disturbed sleep on health.

Some researchers have tried to assess the economic damage from sleep disorders and wakefulness. Although these estimates are indicative, they allow us to assess the extent of the damage. In one such study, it is estimated that the total economic loss is approximately $ 100 billion. In another study, the possible damage from accidents involving sleep disorders is estimated at $ 50 billion.

[14], [16], [18], [19], [22], [23],