Individual Traits of chronics and recente insomniacs

According to the 3P model (e.g. Morin, 1993) insomnia results from the interaction of predisposing, precipitating and perpetuating factors. Although some of them have been empirically identified (e.g., Tan et al. 1984), their interaction has not been systematically studied yet. The present research had two objectives, organized in two studies: (a) to evaluate whether the three classes of factors discriminate subjects reporting chronic insomnia and subjects who do not report any sleep disorder. (b) to evaluate, among subjects reporting sub-criteria insomnia, whether the three classes of factors discriminate subjects who after 4 months develop a recent insomnia and subjects who report a complete remission. Methods: (a) In the waiting rooms of general practitioners 931 patients voluntarily filled in a Sleep Disorders Questionnaire (SDQ, Violani et al. in press), which classifies subjects in three groups: I: subjects reporting chronic insomnia according to the DSM IV criteria; N: subjects who do not report any sleep disturbance; S: subjects complaining insomnia without meeting all DSM IV criteria. A total of 778 subjects screened by the SDQ accepted to fill in at their home the following questionnaires: a Family History of Insomnia form; the Big Five Questionnaire (BFQ); the Coping Inventory for Stressful Situations (CISS); the Symptom Rating Test (SRT); the Social Readjustment Rating Scale (SRRS); a questionnaire on sleep hygiene. A total of 441 subjects returned the questionnaires. Among them, the 74I and 56N were compared by a discriminant analysis. (b) A total of 214 subjects, classified as S, were reached by phone after 4 months and completed again the SDQ and the SRRS. Among them, 38 reported a DSM IV insomnia and 33 reported a complete remission. Individual characteristics of these two groups were compared by a further discriminant analysis. Results: (a) The analysis showed a significant discriminant function [Lambda–Wilks = 0.352; F(6,116) = 35.62; P < 0.0001] with sleep hygiene, depression, age, somatization, problem oriented coping and familial history of insomnia discriminating between I and N subjects. The model classifies correctly 92% of subjects. (b) The analysis showed a significant discriminant function [Lambda–Wilks = 0.508; F(10,60) = 5.8111; P < 0.0000] with somatization, age, familial history of insomnia, emotion stability, occurrence of stressful-life events, problem oriented copying and emotion oriented copying discriminating between subjects who have developed a insomnia and subjects who remit insomnia symptoms. This model classifies correctly 83% of subjects. Conclusions: Results show that poor sleep hygiene and depression characterize subjects reporting chronic insomnia at T1, but not recent insomniacs. When stressful life events precipitate insomnia, copying styles contribute in precipitate a full blown insomnia in predisposed individuals (with familial history of insomnia, greater age and somatization). Factors influencing the maintenance and formation of insomnia are different.