During the year their insomnia began, chronic insomniacs experienced a greater number of stressful life events compared with previous or subsequent years and compared with good sleepers. In addition, among the life event categories assessed, insomniacs reported a greater number of undesirable events, particularly events related to losses and to ill health. They also had lifelong histories of more illnesses and somatic complaints, beginning with more childhood illnesses and more childhood problems related to eating and sleeping. During childhood, insomniacs reported more frequent discontent with their families, and prior to the onset of insomnia, they had less satisfying relationships with their parents as well as problems in other interpersonal relations and in their self-concepts. Currently, insomniacs felt considerably less satisfied with their lives, had lower self-concepts, and had greater difficulty with interpersonal relationships. Thus, stressful life events, mediated by certain predisposing factors of personal vulnerability, were found to be closely related to the onset of chronic insomnia.