The results of interpreting epidemiological data concerning insomnia differ depending on the symptoms taken into account. The prevalence of insomnia without the restrictive criteria is about 30% of general population while about 6–10% of population suffers from more severe forms of insomnia with daytime consequences. Quality of life studies invariably present loss in the quality of life of insomnia patients. Insomnia has been established as a risk factor for developing depression and various physical disorders. Early recognition of insomnia might reduce several health risks.