Insomnia is the most common sleep disorder, occurring more frequently with increasing age and among women.1-3 The onset of insomnia is usually associated with stressful life events. Increased prevalence also has been associated with emotional stresses, psychologic disturbances, and lower socioeconomic status. Further, insomnia is associated with increased morbidity,4 and possibly mortality,5 rates, as well as with the potential development of major psychiatric disorders.6 Chronic insomnia is difficult to treat and has major psychosocial consequences, including its frequent negative impact on the patient's family and employment. Thus, there is a great need for the development of effective prevention and treatment strategies for this disorder.
One strategy for the prevention of chronic insomnia is to search for and identify risk factors or high-risk groups that tend to be associated with the development of this condition. The results of the study by Klink et al7 indicate that