Attention, stress and negative emotion in persistent sleep-onset and sleep-maintenance insomnia

This study investigated the relation of negative emotions, attention and stress to sleep parameters in insomniacs. It also assessed whether sleep-onset insomniacs differ from sleep-maintenance/mixed insomniacs in the relations of these variables to sleep parameters. Fourteen sleep-onset insomniacs, 13 sleep-maintenance or mixed insomniacs and 13 normal sleepers were recruited using two sequential questionnaires. The groups differed significantly on diagnostically relevant sleep parameters, assessed over 1 week by sleep diary. After completing standard anxiety, anger and depression inventories, subjects participated in two laboratory procedures during which electrophysiological responses were recorded: orienting response habituation and emotional stress elicitation. The 28 significant correlations of sleep parameters with emotion, habituation and stress measures averaged r = 0.415. In multiple regression analyses, emotion, attention and stress variables accounted for an average of 41% of the variance in sleep parameters (mean R = 0.64). Discriminant function analysis using these variables correctly classified 66% of the subjects into the three groups. It was concluded that negative emotions, stress responsiveness and attentional factors interact to influence insomnia.