[Lack of sleep and insomnia. Impact on somatic and mental health]

Lack of sleep and insomnia need to be viewed differently. Lack of sleep implies a shortening of the habitual sleep duration due to external circumstances or motivational factors. Insomnia, in contrast, is defined as a sleep disorder due to unknown reasons for the afflicted subjects. People with insomnia suffer from being unable to sleep, in spite of adequate external circumstances. Research on lack of sleep/shortened sleep duration has focused on relationships with somatic and mental health. Longitudinal studies revealed that a shortening of sleep duration (< 6 h) is associated with an increased risk for the metabolic syndrome and cardiovascular diseases. For sleep duration and mortality, a U-shaped relationship was found, indicating that both shortened (< 6 h) and prolonged sleep durations (> 8 h) are associated with increased mortality. Similar, albeit weaker, correlations were described for insomnia and somatic health. In addition, insomnia is a risk factor for the development of mental disorders, especially depression. These relationships suggest that the area of sleep and sleep disorders should be integrated into everyday medical practice and that preventive approaches to somatic and mental disorders should encompass the topic of sleep to a much stronger extent than currently practiced.