Brain reactivity to emotional stimuli in primary insomnia

Objectives: Insomnia is highly comorbid with psychiatric disorders and, at least with respect to major depression, it has been found to be a clinical predictor. The psychobiological mechanisms, however, underlying this relationship are not yet fully understood. Heightened emotionality has been proposed to be a possible mediating factor. Supporting evidence refer to sleep deprivation studies and studies evaluating the role of sleep with respect to emotional memory. Moreover, studies on individuals exposed to chronic life stresses have shown that this condition is associated with sleep disturbances and increases the risk for emotional exhaustion. Neverthless, there is a surprising lack of studies evaluating emotion using physiological indeces in clinical samples of insomnia. Our main objective was to evaluate brain reactivity to emotional stimuli in patients with primary insomnia and in good sleepers. Methods: Patients with primary insomnia (n = 22) and healthy controls (n = 40) were presented with different blocks of neutral, negative, and sleep-related negative pictures during an fMRI task. Neutral and negative pictures were taken from the International Affective Picture System (IAPS), while sleep-related negative pictures were previously validated. Stimuli were matched for valence and arousal levels. All participants previously underwent two consecutive nights of polysomnographic recordings in order to exclude those with other sleep disorders. Results: Preliminary results are consistent with the hypothesis that people with insomnia present altered emotional responses in limbic areas to negative stimuli especially when related to the experience of the symptoms. Specifically, we found that patients with primary insomnia responded with increased amygdala activity to sleep-related negative stimuli as compared with good sleepers. Conclusion: People with insomnia might develop an emotional bias to stimuli related to sleep which would be associated to increasing rumination and preoccupation about the consequences of bad sleep. Clinical implications of the present findings, which need confirmation by further investigation, suggest that adding an emotional regulation component to standard therapy for insomnia might be effective to ameliorate sleep and to prevent the development of depression as a public health priority. The study 'Brain reactivity to emotional stimuli in primary insomnia' has received funding from the European Community’s Seventh Framework Programme (People, Marie Curie Actions, Intra-European Fellowship, FP7- PEOPLE-IEF-2008) under grant agreement n_ 235321.